AGCO Automotive Vehicle Questions Page

 AGCO Automotive Vehicle Questions
Alignment, Frame, Wheels & Tires
QUESTIONS
  1. A friend told me that aircraft use nitrogen to fill their tires. Should I consider it for my vehicle?
  2. A friend told me there is a specific procedure for tightening lug nuts, is this correct?
  3. A nail punctured one of my tires and my tire warning light came on. I put tire sealant in the tire and inflated it. The light went off, but now it is back on and filling the tire does not make it go off.
  4. A tire store broke three of my lug studs, trying to rotate my tires. They say the last person who installed the wheels caused the damage. Who do you think is right?
  5. A tire store recently told me I needed new tie rod ends. They squeezed the tie rod with a large pair of pliers and showed me the movement. Should I let them replace the tie rods or take it to an alignment specialty shop?
  6. After being in an accident, my car does not drive the same as before. All of the body panels fit well and the wheel alignment is set. Could it still have a bent frame?
  7. After buying new tires my car has a vibration or shimmy in the steering. I had the balance checked and it is okay.
  8. After having my tires rotated, the rear of my expedition sinks down over night. Do you think this problem is related to the tire rotation?
  9. After having the rack and pinion replaced, the steering wheel in my vehicle is not centered when I drive straight. How do I center the steering wheel?
  10. After replacing the battery in my Saturn ION, I noticed the power steering was hard to turn and there was a warning light on the dash. Where is the power steering reservoir?
  11. After rotating my tires there is a distinct whine noise when I drive.
  12. Are cracks in a tire sidewall dangerous?
  13. Are there any advantages to the larger diameter wheels and tires on newer vehicles?
  14. At what mileage should I get a wheel alignment?
  15. Buying a new set of tires, I was told my ball joints were bad. I have no symptoms and no tire wear, should I be suspicious?
  16. Buying a set of tires, the salesman tried to sell me nitrogen to fill them. Is using nitrogen to fill tires worth the expense?
  17. Can a bad tie rod cause my car to pull to one side when driving?
  18. Can a bent frame cause a bumping noise when I drive?
  19. Can a cracked frame be repaired?
  20. Can a new tire be out of round?
  21. Can a new tire that was just installed be out of balance?
  22. Can a torn tire bead be repaired?
  23. Can a vehicle being out of alignment cause a flat tire?
  24. Can a vehicle ever be the same after the frame has been bent?
  25. Can frame damage to a vehicle cause engine damage?
  26. Can I add grease fittings to my suspension which does not have them?
  27. Can I lower my car without causing problems?
  28. Can I substitute a lower rated tire on my vehicle that specifies “V” rated tires. I have been told this is only a speed rating.
  29. Can offset wheels cause damage to my vehicle?
  30. Can parking with my wheels turned affect wheel alignment?
  31. Can rotating tires cause a vehicle to be go out of alignment?
  32. Can the air suspension on my Ford be replaced with regular springs?
  33. Can the strength of a bent frame be preserved when it is straightened?
  34. Can two tires have the same DOT number?
  35. Can using nitrogen in tires give better fuel mileage?
  36. Can wheel alignment cause the rear tires to make noise when driving?
  37. Do wheel weights come in more than one style? The weights on my wheels do not seem to fit well.
  38. Does a bent wheel cause tire wear?
  39. Does a crooked steering wheel necessarily mean bad wheel alignment?
  40. Does a torn ball joint boot mean the part has to be replaced immediately?
  41. Does a torn tie rod boot mean I should immediately replace an outer tie rod?
  42. Does crossing radial tires cause damage? I was told the belts would separate if I crossed my tires from side to side.
  43. Does my vehicle pulling to one side mean I need an alignment?
  44. Does parking with wheels in the full lock position cause a vehicle to go out of alignment?
  45. Does the body need to be removed to repair frame damage?
  46. Does tire sealant ruin TPMS sensors?
  47. For best ride, what is the minimum air pressure I should use in my tires?
  48. Getting new tires, I was told of difficulty aligning the vehicle because struts were going out. They told me that it would cost roughly $### and if done with in 6 mo they would not charge for an alignment.
  49. How can I be sure the unibody or frame on my vehicle was properly repaired after a collision?
  50. How can I calculate the effect that different size tires will have on my speedometer reading?
  51. How can I keep my tire valve stems from dry rotting?
  52. How can I tell how many plies my tires have?
  53. How can I verify the accuracy of my tire pressure gauge?
  54. How do I determine the ply rating of the tires on my light truck?
  55. How do tire-pressure monitoring systems, without sensors in each wheel work?
  56. How do you bleed air from a newly installed power steering system?
  57. How does the bead of a tire normally get torn?
  58. How does tire size affect the reading of my speedometer?
  59. How likely is it to have four out of round tires on a vehicle?
  60. How little imbalance will cause a vehicle to shimmy?
  61. How long does it take to rotate tires?
  62. How much pressure do power steering lines have to hold?
  63. How much pressure does it take to straighten a frame?
  64. How much will a bad alignment shorten tire life?
  65. How often should I have my vehicle’s alignment set?
  66. How often should I rotate my tires?
  67. How tight should my wheel lugs be?
  68. I am interested in lifting the suspension on my truck. What type problems might I expect?
  69. I am replacing the tires on my vehicle and want a little more traction. Can I replace them with a wider tire?
  70. I bought a new set of tires and now have a shimmy and vibration. The tire store has balanced them several times, but the shake is still there. Another shop checked the vehicle and says the tires are out of round. How do tires get out of round?
  71. I bought a new set of tires and the old tires had no uneven wear. Do I still need an alignment?
  72. I bought tires and the shop told me the lug nuts on my car were worn out and should be replaced. Is this a scam?
  73. I do not drive my vehicle very much. Even though the tread is good, I have been advised the tires are eight years old and should be replaced.
  74. I do not rotate my tires and they do not wear and seem to last a very long time?
  75. I find wheel weights are very unattractive on my wheels. Why can’t all of the weights be put on the inside where they don’t show?
  76. I had a flat tire and the tire store refused to repair it because the tire was seven years old. Do I have any recourse?
  77. I had a suspension noise on bumps and had the front McPherson struts replaced. The noise is still there, could it be a bad strut?
  78. I had the intermediate steering shaft replaced on my Suburban for a clunk noise in the wheel. A few months later the noise returned. Could it be a bad shaft?
  79. I have a loud knock noise under my Ford Sport Trac and was told the frame to body cushions are bad. Shouldn’t these cushions last the life of the vehicle?
  80. I have a sports car and am very concerned with air pressure. What is the best tire pressure gauge I can get?
  81. I have a vehicle with very high milage [200,000] and need to replace the rack and pinion. I have replaced most parts of the front suspension except the lower control arm bushings. How long do they last?
  82. I have a wobble in my steering wheel that starts when the car starts to roll. At about 10 to 15 MPH it is very noticeable but gets better at higher speed.
  83. I have been told I should balance my tires every time they are rotated for best life, what is your opinion?
  84. I have been told if I use the temporary spare tire, I must put it on the back only (i.e., if a front tire goes flat I need to put a back tire in its place and put the spare on the rear.) Others say this is a myth. What is the official answer?
  85. I have been told my Ford Expedition needs cams installed before it can be aligned. Is this true and why is it built that way?
  86. I have had my car aligned several times and the steering wheel is not centered when driving straight.
  87. I have replaced the inner tie rods on my vehicle three times in 60,000 miles. What could be the cause?
  88. I heard there was a recall on tire valve stems, how can I check to be sure mine are okay?
  89. I just bought a new vehicle and the tires are marked maximum pressure 44 PSI but the owner manual says 32 lbs front and 30 lbs rear. What pressure should I use to maximize the life of my tires and safe handling?
  90. I lost the key to my wheel locks. How can I get the wheels off?
  91. I recently bought tires and was told the valve stems on my vehicle should not be replaced. Is this correct?
  92. I replaced the rear air suspension bags on my Lincoln and now the rear is too high and will not come down.
  93. I struck a curve and blew out a tire. The wheel, tire and front struts were replaced, but the alignment could not be set because there was no adjustment. Can anything be done?
  94. I take very good care of my tires, but the treads have come apart on three of the four?
  95. I want to install a larger set of mud grip tires on my truck. Will this affect the computers?
  96. I was told a tire was causing my car to pull. The term used was conicity. Can camber or caster be adjusted to compensate?
  97. I was told my rack and pinion was bad, but I have no symptoms?
  98. I was told my tire was separated, what does that mean?
  99. I was told the yellow dot on the side wall of a tire should be aligned with the valve stem. My new tires have a yellow and red dot, what does that mean?
  100. In an emergency stop I locked up the brakes on my vehicle. After that I noticed a distinct vibration when driving. The tire store says the tires are flat-spotted. What does that mean?
  101. Is a frame heated when it is straightened?
  102. Is a road hazard warranty on new tires worth the money?
  103. Is buying tires online a good idea?
  104. Is it better to move an out of balance tire to the rear?
  105. Is it possible for a vehicle with a proper wheel alignment to still pull to the right or left?
  106. Is it possible for two tires have the same serial number?
  107. Is it possible to weld cracks in a unibody vehicle?
  108. Is it true that plugging a tire with a string type tire plug will void the warranty and if so, why?
  109. Is steering wheel shimmy a symptom of my rack and pinion wearing out?
  110. Is the body of a vehicle removed to straighten the frame?
  111. My cars pulls when driving. It may pull right and then pull left and then right again and so on. The tire store told me this was impossible, it was just the roads. Do you have any ideas?
  112. My Chevrolet Silverado has the typical steering column clunk. Does this affect my wheel alignment?
  113. My Lincoln Town Car squats down in the rear at night. Strangely when I start it in the morning it levels out again. What do you think would cause this?
  114. My new tire has a dimple in the sidewall, an area that dents in. The tire store says it is not a problems should I be concerned?
  115. My new tires have a small red dot on the sidewall. Does the red dot mean anything?
  116. My new vehicle pulls to the right when I drive. The dealership told me the alignment is within specifications and it pulls because all roads lean to the right for drainage. Does this sound correct?
  117. My owner’s manual states 30 PSI pressure for my tires and I am careful to maintain this. The first set of tires wore properly, but my next set is wearing on the shoulders. The tire shop says my tires are under-inflated.
  118. My tires are worn out, should I replace them before I have the vehicle aligned?
  119. My tires keep going out of balance. I have had them balanced several times but my steering wheel still shakes.
  120. My truck keeps breaking the transmission mount. Within six months of replacement it breaks again. Is this just bad parts?
  121. My vehicle does not have a power steering pump, how does the power steering work?
  122. My vehicle has always driven straight. I replaced the tires and now there is a pull to left when driving. Could the alignment have suddenly changed?
  123. On a vehicle, what is the difference between a chassis and a frame?
  124. One wheel on my vehicle keeps coming loose. Last time, I tightened the lugs more than normal, but it still came loose. What could cause this?
  125. Pricing aftermarket wheels I find they are much less expensive than the originals, is there a quality difference?
  126. Recently I damaged a tire. The other three tires have about 50% tread remaining. The tire store insisted on putting the new tire on the rear. I think it should go on the front?
  127. Should a torn boot on the rack and pinion be replaced immediately?
  128. Should I buy road hazard warranty on new tires?
  129. Should lug studs be lubricated when installing lug nuts?
  130. The air pump on my Lincoln Town car seems to run a lot, do you think the pump is bad?
  131. The motor on my General Motors electric power steering had to be replaced. Should I have the wheel alignment checked?
  132. The steering wheel does not point straight when I drive straight. I had a wheel alignment and the wheel is still crooked. What could cause this?
  133. The steering wheel in my vehicle shakes back and forth when I reach about 45 mph. It seems to go away at other speeds, do you think the alignment could be the cause?
  134. The Z rated tires, recommended for my vehicle, are very expensive. Can I use a lower rated tire if I do not drive fast?
  135. There is a clunking noise in my Silverado steering wheel. It sounds like something is loose but everything appears to be good.
  136. This is very strange, but my Chevrolet pick up truck wears the rear tires to the inside. This occurs quickly, about 10,000 miles and has happened on two sets of tires. I am told this is not possible as there are no adjustments possible.
  137. Tire wear, inflation pressure and misalignment
  138. What are the benefits of rotating and balancing tires?
  139. What are the signs of bad rack and pinion mount bushings?
  140. What are the symptoms of a bad McPherson Strut?
  141. What are the symptoms of a bent wheel?
  142. What are the symptoms of a tire with a broken belt?
  143. What are the symptoms of an out of balance tire?
  144. What are the symptoms of bad ball joints?
  145. What are the symptoms of bad tie rods?
  146. What causes cracks in the sidewall of tires?
  147. What causes tire noise?
  148. What causes tires to make a roaring noise?
  149. What do the size numbers on my tire mean?
  150. What does air suspension mean?
  151. What does it mean when a vehicle is said to be dog tracking?
  152. What does negative camber mean?
  153. What does SAE 1205-1206 mean with regard to tire valve stems?
  154. What does the term separated mean with regard to a tire?
  155. What does the term speed rating mean in regard to a tire?
  156. What does the term toe mean, with regard to wheel alignment?
  157. What does the term unibody mean?
  158. What does the term unidirectional tread mean with regards to a tire?
  159. What does TPMS mean?
  160. What is a McPherson strut bearing and what symptoms do they normally give when bad?
  161. What is a steering damper?
  162. What is a wheel lock?
  163. What is an out of round tire?
  164. What is four-wheel alignment?
  165. What is meant by match mounting a tire
  166. What is the best tire air pressure gauge?
  167. What is the difference between a strut and a shock absorber?
  168. What is the pressure required for a 245/75R16 tire?
  169. What makes some radial tires cause a vehicle to pull to the right or left when driving?
  170. What symptoms are present with worn tie rods?
  171. When are tires considered worn too much to use?
  172. When I use my truck for towing, the fan hits the fan shroud.
  173. When replacing only two tires on a vehicle, should they be placed on the front or the rear?
  174. When rotating tires, is it ok to cross and/or switch sides, or should you only rotate front to back same side? I heard switching sides can lead to belt damage due to opposite rotation.
  175. When should the struts on my vehicle be replaced?
  176. When should tires be replaced?
  177. Where are Michelin tires made?
  178. Why are cheap tires out of round?
  179. Why are vehicle manufacturers going to electric power steering?
  180. Why do some cars use air suspension?
  181. Why do some race cars fill their tires with nitrogen?
  182. Why do the balance weights keep coming off of my wheels?
  183. Why do “V” rated tires cost more than “H” rated?
  184. Why is there an electrical connection on my power steering hose?
  185. Why would a tire that has no nails or punctures keep losing air pressure?
  186. Why would my car still squeak after having it greased?
  187. Why would my vehicle suddenly go out of alignment and start pulling hard to the right?
  188. Why would putting shorter tires on my car make my speedometer read faster than I am actually going?
  189. Why would the clunk noise in my Sierra Truck steering wheel keep coming back even though the intermediate steering shaft is well lubricated?
  190. Why would the lug studs on my car continue to break? I know they were properly tightened to the specified torque.
  191. Why would the lug studs on my car continue to break? I know they were properly tightened to the specified torque.
  192. Will power steering fluid work in a vehicle that specifies automatic transmission fluid in the steering?
  193. Will putting load range E tires on my truck decrease my fuel milage compared with load C tires.
  194. Will you explain tire dimensions?
  195. With no grease fittings on my vehicle, what can I do to prevent expensive suspension problems?
  196. Would a tire store be liable for an accident if they installed lower rated tires than recommended on my vehicle, and they fail?
  197. Would rotating my tires cause my car to pull to the right when driving?
ANSWERS
  1. A friend told me that aircraft use nitrogen to fill their tires. Should I consider it for my vehicle?

    The Federal Aviation Administration (FAA) specifies nitrogen fill in aircraft tires. This is largely a fire concern. Nitrogen does not support combustion as well as air. In the event of a brake or wheel fire, it is hoped this could be a positive factor. The advantage on an automobile is generally not worth the cost or inconvenience.

    For more information, please see our Detailed Topic Filling Tires With Nitrogen.
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  2. A friend told me there is a specific procedure for tightening lug nuts, is this correct?

    There is a specific torque, for each vehicle and a recommended tightening pattern. I like to torque lug nuts in three stages. For instance if the specified torque is 90 foot pounds, I would complete the pattern at 30 foot pounds and then repeat at 60 foot pounds and finally finish with 90 foot pounds. The tightening pattern normally involves moving to the lug furthest from the last lug tightened. Torque varies greatly from one vehicle to another and service information should be consulted for the proper amount.

    Lug nut torque patterns

    For more information, please see our Detailed Topic Wheel lugs, torque and keeping the wheels on.
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  3. A nail punctured one of my tires and my tire warning light came on. I put tire sealant in the tire and inflated it. The light went off, but now it is back on and filling the tire does not make it go off.

    A vehicle with an in tire pressure monitoring system (TPMS) has a sensor in the tire that reads air pressure. Tire sealant can enter the sensor and quickly cause damage. A proper repair will involve dismounting the tire, repairing the puncture, thoroughly cleaning the interior and replacing the TPMS sensor.

    For more information, please see our Detailed Topic Valve caps and TPMS.
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  4. A tire store broke three of my lug studs, trying to rotate my tires. They say the last person who installed the wheels caused the damage. Who do you think is right?

    Most times, broken lug studs are caused by improper installation. If the studs broke while the lugs were being removed, chances are it was previous damage. If the studs were broken while installing the wheels, I would suspect too much torque being used or the nuts improperly started on the studs.

    For more information, please see our Detailed Topic Wheel lugs, torque and keeping the wheels on.
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  5. A tire store recently told me I needed new tie rod ends. They squeezed the tie rod with a large pair of pliers and showed me the movement. Should I let them replace the tie rods or take it to an alignment specialty shop?

    Squeezing tie rods with a pair of pliers is improper and will often damage good tie rods. Best is to take the vehicle to another shop and have it properly inspected.

    For more information, please see our Detailed Topic, Properly Checking Tie Rod Ends.


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  6. After being in an accident, my car does not drive the same as before. All of the body panels fit well and the wheel alignment is set. Could it still have a bent frame?

    The term frame is often used interchangeable with unibody, though they are technically different. The precision required in unibody repair is normally greater than required with a frame. It is quite possible there is still damage that was not addressed. Body repair shops are very good at cosmetic work, because that is the bulk of what they do. Intricate frame and suspension problems often require a specialist to locate and correct.

    See our Detailed Topic Frame Repair, The Good, The Bad and The Ugly for more information on hidden chassis damage.
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  7. After buying new tires my car has a vibration or shimmy in the steering. I had the balance checked and it is okay.

    Balance is one component of vibration. A tire that is not round will also vibrate, even though it is balanced. For instance a square block could be balanced, but would not roll smoothly. A well equipped shop should have an indicator for measuring tire run-out. The device rolls or slides on the tire tread, as the tire is rotated and indicates the amount the tire is out of round. No run-out is preferred, but anything over 1/16" inch will normally cause a noticeable vibration.

    See our Detailed Topic article Ruining New Tires for far more details.
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  8. After having my tires rotated, the rear of my expedition sinks down over night. Do you think this problem is related to the tire rotation?

    Suspension air bags are made of rubber and have a life. They should be inspected annually after six years and replaced as soon as they show cracking. Chances are the bags will be dry rot cracked. When the vehicle was raised for the rotation, the bags extended further than normal. This may have revealed the problem, but really did not cause it. An inspection of the system should tell for certain.

    For more information please see our Detailed Topic Ford Air Suspension Problems.
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  9. After having the rack and pinion replaced, the steering wheel in my vehicle is not centered when I drive straight. How do I center the steering wheel?

    Replacing the steering gear should include resetting wheel alignment. Centering the steering wheel is part of any proper wheel alignment. The steering wheel is locked in a centered position while adjusting the right and left tie rods until the distance between the front of the tires and the rear is correct [toe] and the front tires track straight with the rear.

    For more information, please see our Detailed Topic, Wheel Alignment, Toe and Tracking.


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  10. After replacing the battery in my Saturn ION, I noticed the power steering was hard to turn and there was a warning light on the dash. Where is the power steering reservoir?

    Many vehicles today use electric power steering and have no steering reservoir. Instead an electric motor and series of sensors provides power assist. These systems are very susceptible to voltage and easily damaged. Check the fuse box to see if the power steering fuse is blown.
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  11. After rotating my tires there is a distinct whine noise when I drive.

    If the noise was not present before rotating and started immediately after, a likely cause is the tires. Rear misalignment of the suspension can cause rear tires to wear in spots. This comes on slowly and because the rear of a vehicle is relatively light, the noise is not noticeable. When the tire is moved to the front, the weight of the power-train is being supported. This causes the noise to become far more noticeable.

    To confirm this theory, closely examine the tire tread. Run your hand over the tread and see if you feel high and low spots. Next rotate the tires to the original positions. If the noise goes away, this is likely the problem. Replacing the tires is the only cure, but the original cause must be found are it will recur. A quality suspension shop should be able to diagnose the root cause for you.
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  12. Are cracks in a tire sidewall dangerous?

    Even very minor cracking should be cause for concern. One cause of cracking is age. Many experts and vehicle makers state six-years is the maximum safe life of a tire. The cracking can be a symptom of even more serious problems. See our Detailed Topic article Old Tires With Good Tread for far more details.

    Severe cracking at low age is usually a defect in the tire, a deficiency in manufacturing. This can be very dangerous and the tire should not be used.

    Defective tire with severe cracking at after only three years age
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  13. Are there any advantages to the larger diameter wheels and tires on newer vehicles?

    The only advantage is appearance and only if the look appeals to you. They are considerably more expensive to replace, give a rougher ride, compared to a taller sidewall and are easier to damage when hitting pot holes. They may also make the vehicle stand out and provide an inviting target to thieves.
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  14. At what mileage should I get a wheel alignment?

    Wheel alignment is NOT dependent on mileage. Wheel alignment only needs to be set when there is a problem. Some vehicles may never require alignment. Symptoms of possibly needing wheel alignment include, tire wear, a pull to the right or left when driving and a steering wheel that is not centered, when driving straight. With none of these symptoms it is doubtful a wheel alignment is needed.

    For even more information on wheel alignment, please see our Detailed Topics article, Wheel Alignment Myths.


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  15. Buying a new set of tires, I was told my ball joints were bad. I have no symptoms and no tire wear, should I be suspicious?

    With no tire wear or other symptoms, I would look for a second opinion or a better explanation. Ball joints can have a significant amount of up and down movement, when unloaded. This in itself is not a reason to condemn the ball joint, unless there is also side to side movement.

    Please see our Detailed Topic All About Ball Joints for more information.
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  16. Buying a set of tires, the salesman tried to sell me nitrogen to fill them. Is using nitrogen to fill tires worth the expense?

    In automotive and light truck tires nitrogen fill is more of a gimmick than an advantage. Nitrogen molecules are larger than oxygen and for that reason are thought to leak out of tire more slowly. Considering air is about 79% nitrogen already, the difference is almost nil. Buying tires from a business that mounts and balances them properly and uses a quality valve stem will have far more advantages.

    For more information, please see our Detailed Topic Filling Tires With Nitrogen.
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  17. Can a bad tie rod cause my car to pull to one side when driving?

    A seized tie rod could cause a pull but this is fairly rare. Pulling is not a normal symptom of a worn tie rod. Wear causes slack which effects toe and will wear tires and produce slack in the steering.

    For more information, please see our Detailed Topic, Properly Checking Tie Rod Ends.


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  18. Can a bent frame cause a bumping noise when I drive?

    The symptoms of a bent frame can vary widely depending on the nature, severity and position of the damage. A bumping noise may sometimes but not always be a symptom. This is often the result of components moved out of position and striking one another as a result. Other symptoms may be, rapid wear of suspension and drive line parts, tire wear, poor driving and vibrations.

    See our Detailed Topic article Frame and Unibody Damage for far more details.
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  19. Can a cracked frame be repaired?

    Cracks in a frame can be repaired but this requires very specialized welding and metal working techniques. This is a specialty requiring a knowledge of welding, heat affect zones, high-strength-low-alloy (HSLA) metals, stress relieving and more. The metal must be repaired to its original strength but not beyond. Plating and reinforcing the area of the crack can cause stress risers which may create future cracks in other areas. This type repair is best reserved to a frame and unibody specialist.
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  20. Can a new tire be out of round?

    New tires that are out of round tires are actually common. Out of round is a defect, normally built into a tire, rather than something that occurs. Improperly mounting a good tire, may cause damage and make the tire out of round.

    See our Detailed Topic Out of Round Tires for more information.
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  21. Can a new tire that was just installed be out of balance?

    Many new tires are not balanced properly. If either side of the wheel has no weights or multiple weights (more than one on either side) the balance may not be properly done. A change of ride quality, shimmy or vibration, after the installation of new tires is also cause for concern.

    No weights combined with a vibration in the vehicle after installation

    See our Detailed Topic article Ruining New Tires for far more details.
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  22. Can a torn tire bead be repaired?

    Tire beads are almost always torn by improper mounting of the tire. A torn bead is non-repairable and the tire should be replaced. For more information on proper and improper tire mounting, please see our Detailed Topic article Ruining New Tires.
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  23. Can a vehicle being out of alignment cause a flat tire?

    There is no direct correlation between wheel alignment and a flat tire. Lack of wheel alignment can severely wear tires. If a tire were to wear badly enough it could go flat. In this case the flat tire is caused by the wear and the wear was caused by the lack of wheel alignment.

    For even more information on wheel alignment, please see our Detailed Topics article, Wheel Alignment Myths.
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  24. Can a vehicle ever be the same after the frame has been bent?

    The answer depends on two things, the severity of the damage and the skill of the repairer. Damage to the front or rear sections of the vehicle can normally be repaired to like new condition by a skilled frame shop. Damage to the center of the vehicle is much more difficult to repair properly.

    A skilled shop can advise as to the limits of what can be repaired properly. As a general rule, metal that is kinked [bent to a radius of 1/8" or less] may not be repairable. I feel it is a wise idea to have a severely damaged vehicle inspected by a second independent shop, after it has been repaired. This will verify a proper repair or point out problems that should be addressed.
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  25. Can frame damage to a vehicle cause engine damage?

    There are two parts to the answer. The things that cause frame damage often also cause damage to the engine, suspension and drive line. For instance, running into another vehicle can easily break mounts off the engine, smash air flow meters and sensors. Running into a ditch can smash an oil pan and break an oil pump.

    Driving a vehicle with frame damage can also cause damage. The engine is generally mounted to the frame or unibody. With the mounting out of alignment, far more stress is placed on motor mount, drive axles, the transmission, fuel lines, etc. Damage to these components and more are also common on frame and unibody damaged vehicles. The same is true of many other components. For instance, I have seen many radiators and air conditioner condensers with holes caused by rubbing on nonaligned body panels.

    See our Detailed Topic Frame Repair, The Good, The Bad and The Ugly for more information on hidden chassis damage.
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  26. Can I add grease fittings to my suspension which does not have them?

    Modern suspension parts are normally sealed and not able to be greased. This has worked very well and they tend to last a very long time. There is no practical way to add a grease fitting, unless provisions are provided in manufacture of the part. This is less common today, as leaving the fitting off cuts cost. It also helps to protect the joint from improper service. Not carefully greasing can allow contamination to enter the joint. Over-greasing can damage the boot, and cause rapid failure.

    Tie rod with provisions to be greased
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  27. Can I lower my car without causing problems?

    Changing the design height on a suspension will always create problems. The further from stock height the more involved the problems will be. For a lot more information on modifying vehicle suspensions, see our Detailed topic, Lowering and Raising Vehicle Suspensions.
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  28. Can I substitute a lower rated tire on my vehicle that specifies “V” rated tires. I have been told this is only a speed rating.

    The term speed-rating is somewhat misleading. The structural integrity of a tire design is tested by spinning at increasing speed until centrifugal force tears the tire apart. The term “speed rating” arises from the testing method.

    Engineers design suspensions to load tires during braking, cornering and driving. If the vehicle is engineered with a “V” rated tire and a lower rated tire is substituted, handling and safety can be affected. Problems may also appear with irregular wear and vibrations. The least expensive tire is the tire designed for the vehicle.

    For more information, please see our Detailed Topic, Can I Substitute A Lower Speed Rated Tire.


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  29. Can offset wheels cause damage to my vehicle?

    Offset, the relative position of the inside mount surface to the actual center of the wheel, has much to do with how the suspension is loaded. As the center line of the wheel moves farther outward from the inside mount surface of the wheel, the load on the suspension may drastically increase. This extra-load can quickly destroy wheel bearings and suspension support bushings.

    Negative offset in a wheel

    Excess offset also increases the scrub radius or the amount the tire drags when the steering is turned. This is due to the pivot point of the suspension remaining fixed while pivot point of the suspension no longer aligns with the center of the wheel. Forward and rearward travel of the wheel when turning is increased often resulting in the tire striking the fender when the wheel is steered.


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  30. Can parking with my wheels turned affect wheel alignment?

    Wheel alignment is secured very well, usually by threaded fasteners or cams. Parking with the wheels turned will have no affect on the wheel alignment.

    For even more information on wheel alignment, see our Detailed Topics article, Wheel Alignment Myths.
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  31. Can rotating tires cause a vehicle to be go out of alignment?

    Rotating tires will not affect vehicle alignment. Tires very often cause driving issues, such as pull, noise and vibration. Moving tires during rotation may cause existing problems to be revealed. For instance a tire with conicity may be hardly noticeable on the rear and cause a pronounced pull when rotated to the front.

    For more information on how a tire can cause a vehicle to pull right or left, please see our Detailed Topic Tire Conicity and Radial Pull.


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  32. Can the air suspension on my Ford be replaced with regular springs?

    It can be done, but the results are normally very poor. A great deal of engineering went into the air suspension used on Ford. It is relatively problem free, provides a great ride and good handling. It also allows the suspension to adapt to changes in weight, preventing tire wear. The retro-fit kits that I have seen, are low-quality and greatly diminish the vehicle performance.

    I feel a much better plan is to learn to avoid problems with the system. To do this, see our Detailed Topic article Ford Air Suspension Problems.
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  33. Can the strength of a bent frame be preserved when it is straightened?

    Proper straightening of metal will not weaken it and a frame is no exception. A frame repaired by a skilled professional will be as strong as the original. This pre-supposes the frame has not previously been damaged by improper repair. Over-heating metal, improperly working metal and repair of metal that is kinked can result in weakening. It is very important to select a true professional for frame repair. Once metal is damaged by improper repair, it can rarely be restored.
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  34. Can two tires have the same DOT number?

    Yes, the DOT code is not a unique serial number. Instead it identifies when and where the tire was produced. Many tires of a given size and model produced on a given day may all share the same DOT number.
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  35. Can using nitrogen in tires give better fuel mileage?

    No, nitrogen nor any other gas in a tire can influence fuel mileage. The claims by nitrogen-fill proponents compare a tire properly inflated with nitrogen to one under-inflated using air. Their contention is that nitrogen will keep tires inflated better and thus could give better mileage, compared to an under-inflated tire. I think this is misleading at best, as the difference in air retention can be as little as 1.5 PSI per year with nitrogen, compared to air.

    For more information, please see our Detailed Topic Filling Tires With Nitrogen.
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  36. Can wheel alignment cause the rear tires to make noise when driving?

    Technically, wheel alignment causes wear to the tires. Once worn in spots, the tires can produce a roaring noise very similar to a bad wheel bearing. Distinguishing between the two is easiest if the sound changes on different road surfaces. Inspection of the tires normally reveals uneven wear, in spots. Rotating the tires front to rear may also cause the nature of the noise to change.
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  37. Do wheel weights come in more than one style? The weights on my wheels do not seem to fit well.

    Yes wheel balance weights come in a wide variety of styles as well as coated and un-coated. There are gauges that tell which style fits each wheel. Quality shops stock the proper weights for the vehicles they service. Standard weights are natural lead finish and are suitable for steel wheels. Aluminum wheels should use nylon coated weights to prevent corrosion. Coated weights are several times more expensive than un-coated and another sign of a high quality shop.

    See our Detailed Topic Wheel Balance, Shimmy and Vibration for more information.
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  38. Does a bent wheel cause tire wear?

    A bent wheel can wobble, which can cause scallop wear to the tire. The amount of wear, from the bent wheel is normally not excessive. A more prominent symptom is usually vibration. Many people do see excessive tire wear and a bent wheel. They may then assume the wheel is causing the wear. The tire wear is more likely caused by wheel misalignment, resulting from the same impact that bent the wheel.
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  39. Does a crooked steering wheel necessarily mean bad wheel alignment?

    If the steering wheel is crooked, when driving straight, it means the toe adjustment is not correct, side to side. The problem could be either on the front or rear of the vehicle. If this is the case after having the wheel alignment set, it indicates poor workmanship or a lack of diagnostic ability. If a steering wheel that was previously straight, moves to a crooked position, something in the suspension has changed. This is an indication of a problem.

    For more information, please see our Detailed Topic, Wheel Alignment, Toe and Tracking.


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  40. Does a torn ball joint boot mean the part has to be replaced immediately?

    The ball joint boot seals the joint, holds in the lubricant and keeps water and debris out. Once the boot is torn, the joint will fail. The amount of time before the part fails can vary substantially. If the part is not yet worn and giving no symptoms, you can wait, but only if you are willing to regularly inspect the part.

    A torn ball joint boot means imminent failure.
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  41. Does a torn tie rod boot mean I should immediately replace an outer tie rod?

    When the boot tears protection is lost and the tie rod will eventually fail. There will normally be no immediate problem until wear and corrosion occur. At that point the tie rod must be replaced.

    For more information, please see our Detailed Topic, Properly Checking Tie Rod Ends.


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  42. Does crossing radial tires cause damage? I was told the belts would separate if I crossed my tires from side to side.

    Damage from crossing radial tires is a very persistent, false piece of folklore. A particular brand of early design radials did have a separation issue. Crossing was suggested as a possible cause and caught on. Most radial manufacturers today recommend cross-rotation under several circumstances. The only exception is a directional tread pattern. Directional tires will not be damaged but will not flow water out of the tread properly if crossed. This is due to direction of the tire sipes and not the construction of the tire.
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  43. Does my vehicle pulling to one side mean I need an alignment?

    Pulling to one side or the other is one symptom of misalignment. There are also many other things that can result in a vehicle pulling, so it does not necessarily mean the alignment is off.

    Low air pressure in one or more tires can cause the problem even though the alignment is fine. Another common cause of pulling may be the tire. Even new tires can cause a pull. This is considered a defect in the tire and may be covered by the tire manufacturer’s warranty.

    Mismatched tread patterns or tire sizes on opposite sides of the vehicle can also cause the vehicle to pull as can power steering system problems. Most of these symptoms will feel very similar to an alignment problem. If your vehicle pulls to one side when driving, you should inform the shop of the symptom. Allow them to diagnose the problem, rather than requesting an alignment.

    For even more information on wheel alignment, see our Detailed Topics article, Wheel Alignment Myths.
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  44. Does parking with wheels in the full lock position cause a vehicle to go out of alignment?

    A properly set vehicle wheel alignment is very difficult to affect. Alignment settings are generally locked in place. Parking with the wheels turned, even at full lock will not affect wheel alignment.

    For more information, please see our Detailed Topic Wheel Alignment Myths.
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  45. Does the body need to be removed to repair frame damage?

    Properly straightening a frame means reversing the damage that has occurred. The body and frame were joined when the damage occurred and should be repaired in the same manner. Removing the body or any structural components before straightening will normally make the process far more difficult. Body components would only be removed after the frame is straightened. Even if a frame is to be replaced, the best shops will normally pull the old frame into shape before separating the body and chassis.
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  46. Does tire sealant ruin TPMS sensors?

    Tire sealant can quickly destroy tire pressure monitoring system (TPMS) sensors.

    For more information, please see our Detailed Topic Valve caps and TPMS.
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  47. For best ride, what is the minimum air pressure I should use in my tires?

    The amount listed on the door placard or in the owner’s manual is the amount required to safely support the weight of the vehicle and should be considered the lowest pressure to be used.
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  48. Getting new tires, I was told of difficulty aligning the vehicle because struts were going out. They told me that it would cost roughly $### and if done with in 6 mo they would not charge for an alignment.

    It would be unusual for a vehicle with 66,000 miles to need struts. It is also very unusual to hear a worn strut would offer any difficulty in alignment. The offer to wave the alignment charge also sounds very suspect, in my opinion, you can bet the cost is built in. I would definitely seek a professional opinion from a trustworthy shop.

    Original struts are often much higher quality than aftermarket replacements being sold. The originals are designed last at least twice that mileage and normally fail due to poor quality tires, and/or bad strut shaft covers.

    What is important to realize is that many things can be called "replacing struts". For instance there are struts that are not as good when new as the originals are with 120,000 miles. You may be removing a better product than you are installing. These cost about 1/10 the cost of the originals and create a substantial profit for the shops that use them.

    If the struts are bad, there are also many other factors to consider. The two upper strut mounts, two jounce bumpers and two strut shaft covers, are often not included in such estimates. Omitting these items results in what seems to be a lower estimate, while preserving the profit of the shop.

    These items have higher failure rates than the struts themselves and can be replaced for no additional labor when the struts are out. Not replacing these often results in the job having to be done over after a short while and at much greater cost.

    For more information, please see our Detailed Topic, How Do You Know When You Need Shocks or Struts


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  49. How can I be sure the unibody or frame on my vehicle was properly repaired after a collision?

    A leading indication of frame and unibody problems will be tire wear and handling issues. Having a wheel alignment specialist check the steering angles is very helpful, especially if there are any handling or tire wear issues. There are also independent frame specialist in many cities that can measure the chassis and detect remaining damage.

    For more information, please see our Detailed Topic, Spotting Wrecked Vehicles.


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  50. How can I calculate the effect that different size tires will have on my speedometer reading?

    The speed indicated is based on revolutions of the drive axle and the circumference of the tire. A taller tire will have a greater circumference and thus travel further each time it rotates. This will have the effect of indicating a speed lower than actually traveled. The easiest way to see the effect is to use the AGCO Tire Size Error Calculator. Enter the original size specified for the vehicle and any other size and the speedometer error will be calculated.
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  51. How can I keep my tire valve stems from dry rotting?

    Quality valve stems are built to resist ozone which causes cracking. The Society of Automotive Engineers (SAE) has standards for valve stems (SAE 1205-1206.) Millions of cheap substandard valve stems have been recalled because they do not meet this standard. Valve stems are often replaced when tires are replaced, which should be no less than every six years. If quality stems are used, there should be no problem in this time frame.

    Many vehicles with tire pressure monitoring systems or TPMS and sensors in each wheel, have stems designed to last the life of the vehicle. These stems are inspected and only replaced if a problem exist.

    Please see our Detailed Topic Dangerous Valve Stems for more information.
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  52. How can I tell how many plies my tires have?

    On standard load tires the plies will be listed on the sidewall. There are normally two listings, one for the tread and one for the sidewalls. In the image below, tread is two polyester plies and two steel plies which equal four plies. The sidewalls are two ply polyester. This is considered a four ply tire.

    Ply ratings as listed on tire sidewall,

    With load rated, truck tires the markings are different. A series of letter ratings designate the ply rating, as follow.

    Tire ply load ratings

    Load rating, as listed on tire sidewall
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  53. How can I verify the accuracy of my tire pressure gauge?

    There are two primary components to accuracy in tire pressure gauges. The first is repeatability, that is the SAME reading each time. This always precedes the second factor, which is accuracy of the reading. If the gauge does not repeat, accuracy of the reading is irrelevant. Testing repeatability can be as simple as taking multiple consecutive readings from the same tire. Each reading should be the same as the last.

    To test accuracy of the reading you must have a known standard. At AGCO, we use a laboratory certified test instrument and check our gauges against it. Best is to locate such a device to have the accuracy of a gauge verified. It is also important to realize, accuracy and repeatability usually changes over time. Very good gauges change very little or none, while poor gauges may not read correctly even when new.
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  54. How do I determine the ply rating of the tires on my light truck?

    Ply ratings on LT (light truck) tires are usually expressed by a letter designation, following the size. Common ratings are:

    • B for four ply rating
    • C for six ply rating
    • D for eight ply rating
    • E for ten ply rating

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  55. How do tire-pressure monitoring systems, without sensors in each wheel work?

    Systems without in-tire sensors use the vehicle wheel speed sensors. A low tire will be shorter than a properly inflated tire. The shorter height means the low tire must turn faster to keep up with the other tires. By monitoring wheel speed, an onboard computer can infer which tire is low.



    Please also see our Detailed Topic How To Set Tire Pressure for a great deal more information.
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  56. How do you bleed air from a newly installed power steering system?

    In normal cases, fill the system with the proper fluid and leave the cap off the reservoir. WITHOUT STARTING THE ENGINE and with the front wheels off the ground, slowly turn the wheels from right to left and back again several times. Do not turn quickly and do not turn to full lock. Top off the reservoir and repeat until no more fluid is taken in. In more persistent cases it may be necessary to attach a vacuum source to the reservoir while performing the above procedure.
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  57. How does the bead of a tire normally get torn?

    Tire beads are almost always torn by improper mounting of the tire. A torn bead is non-repairable and the tire should be replaced. For more information on proper and improper tire mounting, please see our Detailed Topic article Ruining New Tires.
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  58. How does tire size affect the reading of my speedometer?

    A taller tire has a greater circumference. That means given the same number of axle revolutions, the vehicle will travel faster than with a shorter tire. The speedometer bases its reading on revolutions and assumes the tire is the correct size. Basically a shorter tire will indicate that you are going faster than you are. A taller tire will cause the speedometer to read slower than your actual speed.

    Tire size effect on computer calculations.

    Please see our tire size error calculator where you can compare different size tires and see the effect.
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  59. How likely is it to have four out of round tires on a vehicle?

    Out of round in tires is normally a result of poor manufacturing and/or improper tire mounting. Since all tires on a vehicle are often from the same manufacturer and mounted by the same company, it is quite possible.

    See our Detailed Topic Out of Round Tires for more information
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  60. How little imbalance will cause a vehicle to shimmy?

    This varies a bit based on a few factors. As a general rule, .25 ounce (7 grams) or more will produce a noticeable shimmy. A few factors that affect this include:
    • Low profile tires are more prone to shimmy
    • Suspensions with more caster and SAI designed in are more prone to shimmy
    • Loose suspension parts increase shimmy
    • Wheel offset, positive or negative can increase shimmy
    See our Detailed Topic Wheel Balance, Shimmy and Vibration for more information.
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  61. How long does it take to rotate tires?
    Physically rotating the average set of tires does not take long, perhaps 15 to 20 minutes. Things that can drastically increase that time include:
    • not having the wheel lock key available
    • aftermarket center caps that are very difficult to remove
    • raised or lowered vehicle that are difficult to get on a rack
    • resetting tire pressure monitor system (TPMS) sensors
    Just resetting the TPMS sensors after rotation can easily take more time than rotating the tires.
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  62. How much pressure do power steering lines have to hold?

    Power steering pumps are hydraulic and can produce up to 1200-1500 pounds of pressure. The system operates at much lower pressure, depending on engine speed and restriction to flow. For instance, at an idle and with the steering wheel not turned, pressure may be as low as 250 pounds. With the wheel turned to full lock and the engine speed raised it can approach the maximum.
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  63. How much pressure does it take to straighten a frame?

    Most frame machines can exert 10,000 pounds per square inch (PSI) pulling force. Rarely is over 2,500 PSI actually required. Frame and unibody straightening requires surprisingly little force if properly done. The use of brute force is one sign of an unskilled frame technician. Metal has a memory and will return to the shape into which it was formed when properly handled. The factors affecting force required include:

    1. The vehicle being properly anchored to the frame machine
    2. Use of multiple-simultaneous pulls, rather than single pulls
    3. Pulls being set up to reverse the sequence of damage
    4. Whether the frame or unibody has had poor previous repair
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  64. How much will a bad alignment shorten tire life?

    The extent of tire life that we lose depends on the actual angles that are mis-adjusted and by how much. For instance, improper caster will cause the vehicle to pull one way or the other. As long as all other angles are properly set the effect on tire life will not be drastic. Toe on the other hand will drastically shorten tire life. As an example, for every 1/8 inch of toe a tire will be dragged sideways forty-feet for every mile driven. One-half inch of toe mis-alignment may destroy a set of tires in a few hundred miles. Camber will also wear the tires, but not as drastically as toe.

    A tire showing wear from improper wheel alignment.
    For even more information on wheel alignment, see our Detailed Topics article, Wheel Alignment Myths.
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  65. How often should I have my vehicle’s alignment set?

    Alignment is a repair and not a maintenance item. This means you only need an alignment when there is a problem. A proper alignment usually last several years. In time, suspension components start to wear and the alignment will need to be reset. Also a tire striking something hard enough can cause misalignment.

    Replacing certain suspension components, disassembling the suspension for other repair and collision damage can also necessitate alignment correction. Three main symptoms of improper alignment are:

    1.) Tire wear on one side of the tire or the other.
    2.) The vehicle pulls or veers to one side or the other when driving.
    3.) The steering wheel is not straight when driving straight.

    Any of the above may indicate misalignment of the suspension or you could experience any combination of the three. If you have none of these symptoms likely the alignment is okay. It is also important to remember that things other than alignment may also cause some of these symptoms.

    For even more information on wheel alignment, see our Detailed Topics article, Wheel Alignment Myths.
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  66. How often should I rotate my tires?

    Standard tread pattern tires normally do well rotating between 7,000 and 9,000 miles. Predominately highway mileage normally will extend the interval toward longer recommendation. More in-city use normally requires closer to the lower end. All terrain and mud grip type tires are an exception. They may require more frequent rotation when used on paved roads, perhaps 3,000 to 5,000 miles.

    For more information on tire rotation, see our Detailed Topics article, Tire Rotation.
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  67. How tight should my wheel lugs be?

    There is a specified amount of torque given by the vehicle manufacturer and a preferred pattern for tightening the lugs. The actual torque depends on the diameter, thread pitch and material of the studs.

    For more information, please see our Detailed Topic Wheel lugs, torque and keeping the wheels on.
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  68. I am interested in lifting the suspension on my truck. What type problems might I expect?

    Suspension systems are pure geometry. Every angle in the suspension is carefully designed to work with the vehicle at stock height. Raising or lowering the vehicle’s suspension, even a small amount will cause problems. The camber of the front wheels and the roll center of the vehicle are changed. Once changed, the alignment can no longer be properly set and handling will be affected.

    Ball joints and control arm bushings are also set to work over a specific range of motion. The stock height puts these components in the center of that range. Raising or lowering the suspension will put them very near their limits. When the vehicle now goes through jounce/rebound cycles, these components are over-traveling their design. Rapid suspension wear, tire wear and poor handling are the normal results.

    For a lot more information on modifying vehicle suspensions, see our Detailed topic, Lowering and Raising Vehicle Suspensions.
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  69. I am replacing the tires on my vehicle and want a little more traction. Can I replace them with a wider tire?

    Wider tires alone will seldom add traction to a vehicle. Also most newer vehicles have very limited room for the tire to fit. Wider tires may hit fenders and suspension components. A better answer would be to consult a knowledgeable tire salesperson or study each manufacturer’s website for information.

    Most tire manufacturer’s make tires in several traction ratings. If traction is a concern, selecting a “stickier” tire from a high quality manufacturer is usually a better answer.
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  70. I bought a new set of tires and now have a shimmy and vibration. The tire store has balanced them several times, but the shake is still there. Another shop checked the vehicle and says the tires are out of round. How do tires get out of round?

    Out of round tires are often made that way. Lower quality methods of tire production can produce tires that are simply not round. Beyond that, it is quite possible to ruin a perfectly good set of tires with improper mounting. For more information on improper mounting causing damage to tires, see our Detailed topic, Tire Mounting Problems.
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  71. I bought a new set of tires and the old tires had no uneven wear. Do I still need an alignment?

    If the old tires did not wear, the vehicle drives straight and the steering wheel is centered there is no reason to align the vehicle. Alignment is a repair, not a maintenance item. You only need re-alignment when there is a problem with the alignment.

    For even more information on wheel alignment, see our Detailed Topics article, Wheel Alignment Myths.
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  72. I bought tires and the shop told me the lug nuts on my car were worn out and should be replaced. Is this a scam?

    Lug nuts, especially taper seat type, can wear where the taper meets the wheel. This can be greatly accelerated by over or under tightening of the nuts in the past. Inspecting the lug seat should reveal the wear in the face of the taper. Worn lug nuts can come loose and should always be replaced.

    For more information, please see our Detailed Topic Wheel lugs, torque and keeping the wheels on.
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  73. I do not drive my vehicle very much. Even though the tread is good, I have been advised the tires are eight years old and should be replaced.

    Many experts and vehicle manufacturers recommend tire replacement at six years. They also tend to agree that not being driven may present more of a hazard than being driven. This is a problem on vehicle that are not driven daily, particularly motor homes and classic vehicles. I recommend replacing tires at six years, regardless of the tread.

    See our Detailed Topic article Old Tires With Good Tread for far more details.
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  74. I do not rotate my tires and they do not wear and seem to last a very long time?

    Some tires and vehicles will do fine without tire rotation. Most vehicles tend to wear tires irregularly when they are not rotated. Closely watching the wear pattern on the tires will normally tell which you have. If you are getting good results without rotating, I see no need to change. If there is any doubt, I would go with rotating.

    For more information on tire rotation, see our Detailed Topics article, Tire Rotation.
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  75. I find wheel weights are very unattractive on my wheels. Why can’t all of the weights be put on the inside where they don’t show?

    There are two phases of wheel balance, static and dynamic. Weight is placed opposite heavy spots and in an equal amount to balance the wheel. Placing all of the weight on one side or the other will balance the wheel in that one plane only. This is static balance and is similar to an old style bubble balancer. For instance if a wheel were like a clock face with no width and had a heavy spot at 12 O’clock, the weight would be placed at 6 O’clock.

    The problem is wheels have width and must also be balanced from one side to the other. This is dynamic balance and normally requires weight be added to both sides of the wheel.

    See our Detailed Topic Wheel Balance, Shimmy and Vibration for more information.
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  76. I had a flat tire and the tire store refused to repair it because the tire was seven years old. Do I have any recourse?

    Tires have a life and become unsafe with age. The adhesives that hold them together fails and the rubber degrades. This is so even though they may still have good tread remaining. I know of no tire company that will warranty a tire after six years. The tire company is being prudent in refusing to repair a tire that may not be safe to operate. I would advise replacing any tire over six years of age.

    See our Detailed Topic article Old Tires With Good Tread for far more details.
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  77. I had a suspension noise on bumps and had the front McPherson struts replaced. The noise is still there, could it be a bad strut?

    Anything is possible, but two struts with the same noise would be extremely unlikely. More often the problem is with another component and was mis-diagnosed. Upper strut mounts often cause a bumping noise in the strut area.
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  78. I had the intermediate steering shaft replaced on my Suburban for a clunk noise in the wheel. A few months later the noise returned. Could it be a bad shaft?

    We have found the lower bushing in the steering column is often damaged by the bad shaft. Replacing the shaft moves the bushing and temporarily stops the clunk. A permanent fix normally involves replacing the bushing and the shaft.

    For more information please see our detailed topic GM Steering Column Clunk.


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  79. I have a loud knock noise under my Ford Sport Trac and was told the frame to body cushions are bad. Shouldn’t these cushions last the life of the vehicle?

    Body mount cushions have traditionally lasted the life of most vehicles. In my opinion, the problem with the Ford Explorer and Sport Trac is caused by substandard material.

    For more information on Ford body cushion problems, see our Detailed Topic Ford Explorer and Sport Trac Frame/Body Cushions.
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  80. I have a sports car and am very concerned with air pressure. What is the best tire pressure gauge I can get?

    We have done a considerable amount of air pressure gauge testing and find the PCL, Accura I, to be the finest gauge we have ever used, by a wide margin. Accurate, easy to use, very heavy duty and can measure a wide range of pressure with precision.
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  81. I have a vehicle with very high milage [200,000] and need to replace the rack and pinion. I have replaced most parts of the front suspension except the lower control arm bushings. How long do they last?

    Some go out at low milage, others last the life of the vehicle. A careful inspection is in order. If the bushings are not deteriorated, off center or dry rotted I see no reason to replace them.
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  82. I have a wobble in my steering wheel that starts when the car starts to roll. At about 10 to 15 MPH it is very noticeable but gets better at higher speed.

    Very obvious wobbling at low speeds is often a sign of a separated tire. This is a condition where air leaks from the air chamber and separates the adhesive that holds the plies of the tread together. This often creates a large bump in the tread which causes the wobble.

    As the tire increases speed, the wobble turns into more of a vibration. The condition is very dangerous as the tire can fail unexpectedly at any time.

    A separated tire, dangerous to drive
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  83. I have been told I should balance my tires every time they are rotated for best life, what is your opinion?

    Rotate and balance are two totally separate services. Rotation is maintenance, that is something done for low cost that prevents a higher cost problem. By rotating tires, the wear is more evenly distributed and the tires last longer.

    Balance on the other hand is a repair, in my opinion. A quality set of tires, properly balanced, with the correct weights should stay balanced. The exceptions would be if a balance weight comes off or if the tire is removed from the wheel.

    This is a good example of overall lowest cost. It is less expensive to do business with a shop that has precision balance equipment, all the proper wheel adapters, and a large selection of wheel weights. Even though the initial PRICE of balance in such a shop may be higher, the COST is much lower because it does not have to be redone.

    Rotate tires for best life, but get a good balance the first time on a quality tire. This way you can save the expense of balancing every time you rotate.

    See our Detailed Topic Wheel Balance, Shimmy and Vibration for more information.

    For more information, on a Overall Lowest Cost see the AGCO category, under AGCO Philosophy.
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  84. I have been told if I use the temporary spare tire, I must put it on the back only (i.e., if a front tire goes flat I need to put a back tire in its place and put the spare on the rear.) Others say this is a myth. What is the official answer?

    Actually both are correct, in a way. First, the spare tire is strictly an emergency item, not intended to be used for any length of time. Maximum safe operation is normally under 45 MPH and for short distances only [20-30 miles.]

    With the shorter spare tire on the front, the differential gears are forced to turn very fast. This because the shorter tire must turn faster to keep up with the taller one. This can quickly damage the transmission/differential.

    Now, with the intended use of just getting to a place for immediate service [two to ten miles,] there would be little problem putting it on front. The further driven the greater the chance of a problem. It would always be better to put it on the rear, from that respect.
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  85. I have been told my Ford Expedition needs cams installed before it can be aligned. Is this true and why is it built that way?

    Many vehicles require some addition or modification to facilitate alignment. If the caster and/or camber is out of specifications on your vehicle, it may need cams installed to correct this problem. Vehicle makers can now manufacture vehicles that are properly aligned. If they were built adjustable, each would require a full alignment after manufacture. By building them in alignment and making them non-adjustable they can skip this step, saving money.

    Manufacturers also realize that in time the vehicle may require adjustment and many sell additional parts that make this possible. This is the case with your Expedition.

    Ford original and adjustable camber/caster cam
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  86. I have had my car aligned several times and the steering wheel is not centered when driving straight.

    Centering the steering wheel is a very basic part of an alignment. If the wheel is not centered, the vehicle is not aligned, in my opinion. If the steering wheel is always off in the same direction and by the same amount, this is a simple adjustment. If the amount or position changes, there is something moving in the suspension. In either case, the alignment shop should correct this or let you know what is wrong.

    On vehicles with rack and pinion steering, the rack bushings can slip if they are worn or oil soaked. If the rack moves, even very slightly, the steering wheel will move off center. Adjustment bolts left loose or worn components will have the same effect.

    For more information, please see our Detailed Topic, Wheel Alignment, Toe and Tracking.


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  87. I have replaced the inner tie rods on my vehicle three times in 60,000 miles. What could be the cause?

    If quality replacement parts are being used, you should check for any type of vibration. A shimmy in the steering, caused by an out of round or out of balance tire can quickly destroy suspension components. If there is no shake in the wheel, inner tie rod failure can also be caused by current flow from the engine to the body. Transient current flow can take a path from the engine, through the transmission and drive axles to the steering knuckles. The knuckles connect to the tie rods and are ultimately grounded through the steering mechanism.

    Please see our Detailed Topic Transient Current Flow for much more information.
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  88. I heard there was a recall on tire valve stems, how can I check to be sure mine are okay?

    Valve stems manufactured for Dill between August 2006 and November 2006 were the subject of a recall. The model TR413 and others were involved. It is difficult to identify these stem, without removing the tire from the wheel. Rather, I suggest treat all valve stems as a potential problem. That is, inspect them when tire air pressure is checked. Simply push the stem toward the wheel and check for cracks at the base of the stem. ANY stem showing cracks should be replaced.

    See our Detailed Topic Dangerous Valve Stems for more information.
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  89. I just bought a new vehicle and the tires are marked maximum pressure 44 PSI but the owner manual says 32 lbs front and 30 lbs rear. What pressure should I use to maximize the life of my tires and safe handling?

    The maximum rating listed on a sidewall is the highest pressure that should be put into the tire and not a recommendation. The vehicle manufacturer considers ride quality at least as important as tire wear, so gives a lower rating.

    You may consider one he maximum the other the minimum that should ever be used. I find better tire life is normally achieved at about 10% less than the maximum. This pressure will rise slightly if the tire gets hot [extended driving] and will drop when the ambient temperature drops significantly. Unless temperature change is substantial [50'F or so] it is normally not a crucial factor. Also see our tire pressure article for a great deal more information.
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  90. I lost the key to my wheel locks. How can I get the wheels off?

    A number of tools are available to defeat wheel lock and most shops that service the suspension, and tires will have them. If it is not an emergency, you may also be able to order a replacement key. If the locks are original equipment, the part department of the vehicle manufacture's dealership can order it for you.

    For more information, please see our Detailed Topic, Wheel Locks.


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  91. I recently bought tires and was told the valve stems on my vehicle should not be replaced. Is this correct?

    Vehicles built after 2007 and vehicle with tire pressure monitoring systems (TPMS) often use sensors that are part of the valve stem. These stems are designed to last the life of te sensor, usually seven to twelve years.

    One style of tire pressure monitor sensor.
    See our Detailed Topic Valve caps and TPMS for more information.
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  92. I replaced the rear air suspension bags on my Lincoln and now the rear is too high and will not come down.

    There are several possible causes. One is the height sensor in the rear. If it does not work the vehicle may not bleed air pressure to lower. Another possible cause is the exhaust solenoid in the pump. If the solenoid does not work, air pressure will not be bled off. This solenoid may have been bad and unnoticed when the bags were leaking. The leaking bags serve to bleed excess pressure. Other causes include the solenoids in the bags, though this will normally result in a leaning vehicle unless both fail. Finally the air suspension computer may not send the command for any of the above solenoids to open. Least expensive is to have someone with the proper tooling and experience diagnose which condition exist.

    For more information please see our Detailed Topic Ford Air Suspension Problems.


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  93. I struck a curve and blew out a tire. The wheel, tire and front struts were replaced, but the alignment could not be set because there was no adjustment. Can anything be done?

    Yes, a full service suspension shop with frame equipment should be able to diagnose and repair the problem. Many vehicles built today have little or no adjustments. This is because they are manufactured “in alignment” and will remain so, unless something wears or is bent.

    Diagnosis is the key and once the bent or worn parts are identified they can be replaced or repaired with specialized equipment. Once the vehicle is dimensionally returned to specifications the alignment will also be correct as it was designed.
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  94. I take very good care of my tires, but the treads have come apart on three of the four?

    When the treads separate from multiple tires in a set, the problem is normally age or a defective product. We feel six years is the safe age of a tire. Failure in old tires may be quite common, even though they still have good tread. Because of the good care, your tire tread may have lasted well beyond the useful life of the tire.

    For more information on tire age, see our Detailed Topics article, Old Tires, Good Tread.
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  95. I want to install a larger set of mud grip tires on my truck. Will this affect the computers?

    The various computers on the vehicle do use vehicle speed in their calculations. A larger tire has a greater circumference. This means it travels further for each revolution. Sensors calculate vehicle speed based on the number of revolutions and assume the circumference of the tire is correct. If the tire changes, the calculations are wrong, resulting in incorrect data being used.

    Please see our tire size error calculator where you can compare different size tires and see the effect.
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  96. I was told a tire was causing my car to pull. The term used was conicity. Can camber or caster be adjusted to compensate?

    Conicity is considered a defect in a tire. The effect generally will vary with the speed driven. For instance, hardly noticeable at low speed to quite prevalent at higher speed. If alignment were used to compensate at high speed, the vehicle would pull the other way at low and vice versa. Further, when the tires were rotated or replaced, the alignment would need to be reset. The proper repair is to replace the bad tire(s) and set alignment correctly.

    For more information on how a tire can cause a vehicle to pull right or left, please see our Detailed Topic Tire Conicity and Radial Pull.

    For even more information on wheel alignment, see our Detailed Topics article, Wheel Alignment Myths.


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  97. I was told my rack and pinion was bad, but I have no symptoms?

    Some of the symptoms of a bad rack and pinion can be subtle, especially at first. For instance a leak past the rack seal may be contained by the rack and pinion boots. This may show no leak and may not drip under the vehicle for several months. Eventually there will be noise from a low power steering pump and you may have to add fluid. Another issue could include slack in rack and pinion components. Eventually tire wear will result, but initially may not be noticed. A second opinion may be also be very useful, if you doubt the original diagnosis.
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  98. I was told my tire was separated, what does that mean?

    Separation is a condition where the adhesive that holds the plies of the tire together breaks down. This often creates a large bump in the tread which can cause a wobble or a hard pull to one side. The condition is very dangerous as the tire can fail unexpectedly at any time.

    A separated tire
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  99. I was told the yellow dot on the side wall of a tire should be aligned with the valve stem. My new tires have a yellow and red dot, what does that mean?

    The yellow dot normally indicates the lightest point on the tire and is aligned with the valve stem. The valve stem is normally the heaviest point on the wheel. The red dot is more complex. If the tire has both, ignore the yellow dot. The red dot is basically the point of maximum road force variation, first harmonic. While not exactly, this might be thought of as the stiffest point in the sidewall.

    Some steel wheels have a dimple to mark the lowest spot in the wheel. If so, the red dot aligns with the dimple. If not, or with aluminum wheels, it is placed at the valve stem.

    Yellow and red sidewall dots
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  100. In an emergency stop I locked up the brakes on my vehicle. After that I noticed a distinct vibration when driving. The tire store says the tires are flat-spotted. What does that mean?

    Flat spotting refers to rubber being worn away in one area of a tire. This normally results from sliding the tires on rough pavement, such as a lockup stop or sliding sideways. Flat spotting is not correctable and the affected tires should be replaced to avoid vibration damage to the vehicle.

    Tire tread damaged from sliding on pavement.
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  101. Is a frame heated when it is straightened?

    Heat is very rarely and very judiciously used by a professional. Even when used it is only on certain areas and for a very limited time. This heat is normally less than 500 degrees Fahrenheit and monitored with heat crayons. When a vehicle is properly anchored and multiple, simultaneous pulls are used, heat is normally not required. Instead a procedure known as stress relieving is used.

    Most newer vehicles use high strength steel (HSS,) high strength low allow (HSLA) and martensitic steels. These high-tech steels can quickly be ruined by heat application.
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  102. Is a road hazard warranty on new tires worth the money?

    Road hazard is like a term insurance policy. As the tire wears the amount paid on the claim is steadily reduced. I insure against risk I cannot afford to take, for example, liability on an automobile. Replacing a tire may be aggravating, but it is not likely devastating. I see no sound reason to pay someone to cover such a risk.
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  103. Is buying tires online a good idea?

    Buying tires is a bit different than buying many other things online. Tires have a long life and require service during that life, for instance tire rotation and flat repairs. Many times these services are included in the price you pay locally, but obviously not in an online purchase. Adding these costs to the online tire price may make them comparable to locally purchased tires.

    There is also the issues of finding someone to mount and balance the tires. Shops normally charge a premium when they do not sell the tires. The shop mounting the tire is liable for mishaps in mounting, and they made no profit on the tire to help offset the cost.

    If a tire should fail there is also a problem. The failure will have to be diagnosed, then the tire removed and something put in its place. With online tires, the problem tire(s) must normally be sent back to the original seller for adjustment.

    Like most things in life assuming more risk may save some money. If you allow money for the risk you take and the inconvenience, you may well be able to purchase the tires at full retail locally.
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  104. Is it better to move an out of balance tire to the rear?

    Mechanically there will be little difference. The vibration will simply damage rear components rather than front.
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  105. Is it possible for a vehicle with a proper wheel alignment to still pull to the right or left?

    Many things other than wheel alignment can cause a vehicle to pull when driven. A dragging brake may cause a vehicle to pull. Binding or bent suspension parts can also cause memory steer, or a pull in the direction turned last. Tires that do not match, side to side or low air pressure on one side also causes problems. Even with new, matching tires, conicity can cause a pull in a properly aligned vehicle.

    For more information on how a tire can cause a vehicle to pull right or left, please see our Detailed Topic Tire Conicity and Radial Pull.


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  106. Is it possible for two tires have the same serial number?

    Serial numbers are normally attached to batches of tires and not individuals. The serial number is part of the longer Department of Transportation or DOT number. This series of numbers and letters identifies the month and year of manufacture along with several other pieces of information. The DOT number is the same for all tires in a given batch.

    To learn how to read a tire date code, please see How to read a DOT number.


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  107. Is it possible to weld cracks in a unibody vehicle?

    Successfully welding unibody components requires a knowledge of metallurgy and welding. High strength low allow (HSLA) and Martensitic steels are widely used in modern vehicle construction. Improper welding can easily destroy these metals. Welding must be performed so that heat affect zones do not overlap. Reinforcing the welded areas can also cause stress risers. These can cause future cracking in other areas, due to changes in the flexibility of the repaired member. For all of these reasons, repairing cracks in a unibody should be left to a frame repair and welding specialist.
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  108. Is it true that plugging a tire with a string type tire plug will void the warranty and if so, why?

    String type tire plugs do not meet industry repair standards and may void the warranty on tires. Failure to completely seal the puncture can allow air to force its way between the plies of the tire. When air gets between the plies, it causes them to separate from one another. This condition is known as a tire separation, is very dangerous and leads to tire failure.

    A proper repair involves removing the tire from the wheel and vulcanizing a patch to the inside. This seals the air chamber from the plies and belts that make up the tire. The best method involves a patch that also has a stem manufactured on it. The patch seals the air chamber while the stem seals the original path of entry.
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  109. Is steering wheel shimmy a symptom of my rack and pinion wearing out?

    More likely a worn out rack and pinion is a symptom of steering wheel shimmy. When tires/wheels shimmy, they place a good deal of force on suspension components, such as the rack and pinion, tie rods, struts and ball joints. Shimmy from an out of round tire or bent wheel causes wear. Excess slack from worn parts may allow shimmy to manifest more severely, but such wear is more the symptom than the cause.
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  110. Is the body of a vehicle removed to straighten the frame?

    To the contrary, all sheet metal should be left in place. As damage occurs it travels through the frame and body. With everything in place, and using the proper method, the damage can be reversed. Removing parts will change the rigidity of the structure. This makes it far more difficult to properly repair and secondary damage is often not corrected in the initial pulls.
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  111. My cars pulls when driving. It may pull right and then pull left and then right again and so on. The tire store told me this was impossible, it was just the roads. Do you have any ideas?

    You could a condition called memory steer. That is the vehicle tends to remember the last way it turned and pulls in that direction. Confirmation is relatively simple. Drive the vehicle and note which way it is pulling. Make a hard U-turn in the opposite direction and see if the pull changes to the direction of the last turn.

    Once the existence of memory steer is confirmed, the diagnosis of the cause can begin. It will generally be a binding component in the suspension but can take a good deal of expertise to locate. On vehicles with McPherson struts on the front, binding strut bearings are a common cause. The bearing binds when the strut rotates. This causes the coil spring to twist and then jump, rather than smoothly rotating. On a hard turn the spring does not return to a full center. When trying to drive straight the spring is slightly twisted, causing it to pull the steering in the direction of the last turn.
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  112. My Chevrolet Silverado has the typical steering column clunk. Does this affect my wheel alignment?

    Steering column clunk is annoying, can damage the lower column bushing but will not affect wheel alignment.

    For more information on steering column clunk, please read our Detailed Topic GM Steering Wheel Clunk.


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  113. My Lincoln Town Car squats down in the rear at night. Strangely when I start it in the morning it levels out again. What do you think would cause this?

    The Town Car is equipped with rear air suspension. Two air bags support the rear and height is regulated by a computer controlled air pump. Each bag has a solenoid that prevents leakage. A third solenoid in the pump further prevents leakage. If the vehicle only drops after sitting (over night) the likely cause would be leaking rear air springs. When you start the vehicle, the air pump inflates the springs and so the vehicle rises. Continued operation with the springs leaking, will damage the pump and can cause severe damage to the system. The rear air springs should be checked and replaced to prevent additional expense.

    See our Detailed Topic article Ford Air Suspension Problems for far more details.
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  114. My new tire has a dimple in the sidewall, an area that dents in. The tire store says it is not a problems should I be concerned?

    Dents in the sidewall of new tires are sometimes called undulations. They occur where the plies are spliced together. Most experts agree they pose no danger to the tire and are cosmetic only. This is NOT the same as an area that dents outward and does represent a problem.

    A tire showing an undulation in sidewall
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  115. My new tires have a small red dot on the sidewall. Does the red dot mean anything?

    The red dot is painted on by some manufacturers after tire production. It shows the point of maximum radial force variation. This is roughly the same as the stiffest area of the sidewall. It is somewhat like the highest point in the tires, though not exactly. The red dot is normally aligned with the valve stem, during tire mounting. The valve stem shows the heaviest point of the wheel. This way the area with maximum variation may be partially counteracted by the heavier part of the wheel.
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  116. My new vehicle pulls to the right when I drive. The dealership told me the alignment is within specifications and it pulls because all roads lean to the right for drainage. Does this sound correct?

    All roads do lean, but not always to the right. They lean towards the drainage area which is often on the right. Some roads also lean to the left, when the drainage is on that side. Because most roads lean right, alignment is normally set to compensate for this. This allows the vehicle to drive straight on the majority of roads.

    If the pull is annoying and consistently to the right on all roads there is likely another problem. The alignment needs to be confirmed on a known accurate machine. If the alignment is not the cause, the tires should be crossed and the vehicle driven again. If the direction of the pull changes, you have a tire problem and this must be resolved before going on.

    If the pull persist, the tires are okay and the vehicle is equipped with power steering, the steering should be checked for power steering lead. If that is not the problem, dimensional accuracy of the suspension should be verified by a frame shop.

    For even more information on wheel alignment, see our Detailed Topics article, Wheel Alignment Myths.
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  117. My owner’s manual states 30 PSI pressure for my tires and I am careful to maintain this. The first set of tires wore properly, but my next set is wearing on the shoulders. The tire shop says my tires are under-inflated.

    Tire pressure serves several functions and is dependent on load and tire design. For best tire wear I recommend staying about 10% under the maximum pressure listed on car tires. This pressure will be specified somewhere on the tire’s sidewall.

    The tires that came with the vehicle may have had a designed maximum inflation pressure of 35 PSI. The vehicle manufacturer is normally conscious of ride quality and specifies 30 PSI to improve ride. This extra 4% reduction will increase the smoothness of the ride, because it allows the tire to absorb bumps.

    Many newer tires have designed maximum pressures of 44 PSI and higher. Running these tires at 30 PSI can cause tire wear. I would recommend starting at 10% under maximum or 40 PSI. If the ride feels too harsh, you can reduce this but never below the amount specified by the vehicle manufacturer. Reduction of pressure normally results in more wear on the shoulders of the tires. This method works on passenger or P-rated tires. For truck or LT rated tires a different method is needed. Please see our tire pressure article for a great deal more information.
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  118. My tires are worn out, should I replace them before I have the vehicle aligned?

    Many alignment shops like to see the wear on the tires so they can “custom” align the vehicle to address your specific needs. On the other hand, the final alignment should be set with the new tires on the vehicle. Buying your tires and alignment at the same place will greatly simplify this process. Also if there is a problem in the future, there is only one place to deal with. The key is to buy tires from a place capable of solving problems you may encounter.

    See our Detailed Topic Ruining New Tires for more information.
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  119. My tires keep going out of balance. I have had them balanced several times but my steering wheel still shakes.

    Tires do not go out of balance, either they are not being properly balanced or there is another problem causing the shake. When you ask for wheel balance, you inadvertently have [improperly?] diagnosed the problem. The best shops will not accept such a request and insist on having the symptoms. This allows them to provide the proper fix for the problem.

    Many things can result in shake other than tire balance. Find a shop that asks for symptoms, rather than accepts service request. Asking for a technician to ride with you and demonstrating the shake, will greatly aid in solving the problem.
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  120. My truck keeps breaking the transmission mount. Within six months of replacement it breaks again. Is this just bad parts?

    Some replacement mounts are of very low quality. Continually breaking mounts, sounds like you may have another problem. As a test, remove the mount and support the transmission instead with a block of wood. Run the engine for a few moments and let everything settle. If the transmission moves out of alignment, it is possible the engine is not properly aligned to the chassis. Bent or even bad engine mounts are a possible cause as well as frame damage.

    See our Detailed Topic Frame Repair, The Good, The Bad and The Ugly for more information on hidden chassis damage.
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  121. My vehicle does not have a power steering pump, how does the power steering work?

    Many vehicles use electric motors in the steering column to provide power assist. These systems are electrically powered and do not use a conventional power steering pump.
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  122. My vehicle has always driven straight. I replaced the tires and now there is a pull to left when driving. Could the alignment have suddenly changed?

    Assuming the air pressure in all tires is correct, more likely you are experiencing radial tire pull, also known as ride-disturbance and conicity. This is the tendency of a radial tire to pull or lead to one side. With ride-disturbance the pull normally gets worse as speed of the vehicle increases.

    Diagnosis is simple and straight forward. Verify the direction and intensity of the pull by driving. Temporarily cross the front tires; move the left front to the right front and vice versa. Drive the vehicle again and see if the direction of the pull has changed. If so the tires are the likely cause as nothing else has changed.

    For more information on how a tire can cause a vehicle to pull right or left, please see our Detailed Topic Tire Conicity and Radial Pull.


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  123. On a vehicle, what is the difference between a chassis and a frame?

    The two terms are used interchangeable to describe a separate structure that supports the body of a car or truck. The word chassis may be somewhat older and less used today. Both terms are sometimes incorrectly used to describe supporting structure of any vehicle. Many vehicles built today are unibody construction, not using a separate structure to support the body, thus no frame or chassis.
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  124. One wheel on my vehicle keeps coming loose. Last time, I tightened the lugs more than normal, but it still came loose. What could cause this?

    In almost every case, wheels that get loose are related to damaged lug holes in the wheel. Damage occurs when wheels are run loose or over-tightened. Once the taper of the lug seat is damaged, it will no longer retain the lug nuts. This is very dangerous and can result in lug stud breakage. The wheels should be checked and replaced if this is found to be the case.

    For more information, please see our Detailed Topic Wheel lugs, torque and keeping the wheels on.
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  125. Pricing aftermarket wheels I find they are much less expensive than the originals, is there a quality difference?

    Original equipment wheels are normally of high quality and are specifically designed for the suspension in use. Of the many factors to be considered are those that are familiar such as diameter and width. Wheel offset, whether the wheel is hub or lug centered, lug seat type and the type of construction are also important.

    As a general rule original wheels are forged or cast and machined. Machining produces a wheel that runs true. The center hole of and original wheel is the correct diameter to center the wheel perfectly on the vehicle. The offset [relative position of the mating surface to the center of the wheel] is matched to the suspension. There are usually full provisions for dynamic balance and the lug mount surfaces are often hardened or sometimes have hardened inserts.

    Some cheap replacement wheels may be cast or stamped, rather than machined. This may produce a wheel that does not run true. Strength of the wheel may be compromised and corrosion can be an issue, if substandard alloy is used.

    Original equipment wheels normally run true on the vehicle and give much better overall results than aftermarket replacements. If replacement is considered all the above factors should be considered.
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  126. Recently I damaged a tire. The other three tires have about 50% tread remaining. The tire store insisted on putting the new tire on the rear. I think it should go on the front?

    I agree with the tire store. Whenever less than four tires are put on a vehicle, the new tires should go in the rear. This offers better vehicle control. In the case of one tire, there is also a high probability of the vehicle pulling to one side or the other if the front tires have different amounts of tread. By placing the new tire on the rear, the vehicle is safer and will likely drive better.
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  127. Should a torn boot on the rack and pinion be replaced immediately?

    Rack and pinions are expensive components to replace. When the boot tears, contaminants will enter the unit and cause it to fail. The boots can be replaced at relatively low cost and can prevent rack and pinion failure. I would replace any torn or dry rotted boot immediately to prevent further expense.

    For more information, please see our Detailed Topic, Properly Checking Tie Rod Ends.


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  128. Should I buy road hazard warranty on new tires?

    In my opinion, road hazard is an overpriced, decreasing value insurance policy. Insurance is better suited to risk we cannot afford. An example might be liability insurance. Because we cannot afford the risk, we pay someone else to assume part or all of it for us. This is expensive but better than the alternative. Losing a tire will rarely wipe anyone out financially. Assuming the small risk normally saves far more than any gain.
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  129. Should lug studs be lubricated when installing lug nuts?

    I am unaware of any manufacturer that suggest lubricating lug studs. The specified torque is for a clean, dry stud. Torque is a measure of resistance to turning and not actual clamping force. Lubricating the studs lowers the resistance to turning and the clamping force will be much greater than specified, when the proper dry torque is applied. This could result in damage to the wheels, stretching the lug studs and stripping the treads.

    For more information, please see our Detailed Topic Wheel lugs, torque and keeping the wheels on.
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  130. The air pump on my Lincoln Town car seems to run a lot, do you think the pump is bad?

    If the pump runs more than normal, the system has a leak. When we lose air pressure, the pump runs to replace it. The most common source of leakage is the rear air suspension bags. They tend to dry rot and crack and we lose air pressure. Quick action is important as the pump will be damaged by running too much. This adds considerable unnecessary expense to the repair.

    For more information, please see our Detailed Topic Ford Air Suspension Problems.


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  131. The motor on my General Motors electric power steering had to be replaced. Should I have the wheel alignment checked?

    The motor on GM electric power steering is part of the steering column and does not affect the wheel alignment. On vehicles where the motor is part of the rack and pinion, it could and a wheel alignment check would be in order.
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  132. The steering wheel does not point straight when I drive straight. I had a wheel alignment and the wheel is still crooked. What could cause this?

    A centered steering wheel is the result of properly setting toe, front and rear. With a proper wheel alignment, the steering wheel will be centered. A steering wheel that changes center is another matter. If the amount the wheel is off changes, something is moving, often the rack and pinion mount bushings. If the amount the steering is off center, is constant, alignment is not being properly set. Perhaps the standards of the alignment shop may not be as high as you might like.

    For more information, please see our Detailed Topic, Wheel Alignment, Toe and Tracking.


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  133. The steering wheel in my vehicle shakes back and forth when I reach about 45 mph. It seems to go away at other speeds, do you think the alignment could be the cause?

    The alignment is a very unlikely choice. Shimmy in the steering wheel is normally associated with something that is rotating, such as a tire or wheel. You will feel the symptom of shimmy in certain speed ranges. When the frequency of the vibration matches the frequency of the vehicle structure, the problem will show up. Likely causes include, out of balance tire(s), out of round tire(s), bent wheel(s) or any number of other rotating parts. Important is to give the shop the symptom, rather than requesting a service such as alignment or balance. In this way the likelihood of diagnosing and correcting the problem is greatly enhanced.

    For even more information on wheel alignment, see our Detailed Topics article, Wheel Alignment Myths.
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  134. The Z rated tires, recommended for my vehicle, are very expensive. Can I use a lower rated tire if I do not drive fast?

    The speed rating on tires has to do with the centrifugal distortion the tire can withstand. Using a lower rated tire is not recommended and may adversely affect braking and handling.

    For more information on speed ratings, please see our detailed topic, Can I Substitute A Lower Speed Rated Tire.


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  135. There is a clunking noise in my Silverado steering wheel. It sounds like something is loose but everything appears to be good.

    The Silverado, Sierra, Tahoe, Avalanche and Suburban, as well as many other GM vehicles have a problem with steering column clunk, much as you mention. The intermediate steering shaft is the root cause, but if it continues, the lower steering column support bushing may also be damaged. Repair normally involves replacing the lower bushing and the intermediate shaft with an updated shaft.

    For more information please see our detailed topic GM Steering Column Clunk.


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  136. This is very strange, but my Chevrolet pick up truck wears the rear tires to the inside. This occurs quickly, about 10,000 miles and has happened on two sets of tires. I am told this is not possible as there are no adjustments possible.

    The rear differential of this vehicle is a single piece housing and is not adjustable. That does not mean it cannot get out of alignment. Like any piece of metal, rear differential housings can bend. When they bend, the alignment of the rear wheels are disturbed. Inside tire wear normally indicates either negative camber and/or toe out between the wheels.

    Depending on the position and severity of the bend, these housings can sometimes be straightened. If not, the housing can be replaced, reusing your present gears and possibly axles.

    For more information, please see our Detailed Topic, Wheel Alignment, Toe and Tracking.


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  137. Tire wear, inflation pressure and misalignment

    While improper alignment is a major cause of tire wear, inflation pressure is also very critical. Many people are confused what the proper pressure may be. The sidewall of the tire list one pressure and the vehicle manufacturer may list another. Which is the proper pressure? I think the answer is neither. The proper pressure depends on the desired affect. For instance, the vehicle manufacturer wants the vehicle to ride well. Their recommendation takes this into consideration. If ride is the main concern, this may be the proper pressure. The problem is, it may also allow for some tire wear. The manufacturer's recommendation should be considered the minimum allowable on passenger cars. The pressure on the sidewall of a passenger car tire, is the maximum amount the tire will hold and not a recommendation. I have found very good results by inflating to 10% under this maximum. For instance 40 PSI in a tire that says 44 PSI Maximum. Next watching the tire for signs of wear and adjusting within these given limits allow for fine tuning. If the ride is a little rough decrease pressure slightly. If there is too much shoulder wear increase pressure, staying within the above limits.

    An under inflated tire will wear on the shoulders more than in the center of the tread.
    A tire worn by under inflation.

    By contrast, an over inflated tire wears the center of the tread more than the shoulders.
    A tire worn by over inflation.

    A properly inflated tire wears evenly across the tread.
    A properly inflated tire with normal wear.

    Of course other things can cause tire wear as well. Alignment wear will normally be on one side or the other. This differs from under inflation as the tire is not worn on both sides. The tire below has a good deal of tread on the left, but is ruined because of the wear on the right.
    A tire showing wear from improper wheel alignment.

    This wear could have been prevented by a proper alignment. This 60,000 mile tire lasted about 15,000 before having to be replaced.
    A tire showing wear from improper wheel alignment.

    Certainly there are other things that contribute to tire wear as well. Also see our tire pressure article for a great deal more information. If you have any questions, let the professionals at AGCO check and advise you. AGCO, it's the place to go!
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  138. What are the benefits of rotating and balancing tires?

    Rotation and balance are separate items. Rotation is maintenance and helps even out tire wear between the tires. Front tires tend to wear on the outer edges, because they are turned during steering. Rear tires tend to wear in spots, because the rear on most vehicles are considerably lighter than the front. Rotating tends to even this wear among all four tires.

    For more information on tire rotation, please see our Detailed Topics article, Tire Rotation.

    Balance involves placing weight on the wheels to counteract imbalance in the tires. If the tire is properly balanced when it is first installed [mounted] it should not require balance again. An exception is if the tire is removed from the wheel or a weight comes off.

    For more information on wheel balance, please see our Detailed Topic Wheel Balance, Shimmy and Vibration.
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  139. What are the signs of bad rack and pinion mount bushings?

    As with most things, the symptoms depend on the nature and extent of the failure. An early sign is often a feeling of slack in the steering. A bumping or knocking when turning the wheel can also result. As the bushings get worse the steering wheel will not stay centered. Eventually shimmy in the steering and tire wear can result.
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  140. What are the symptoms of a bad McPherson Strut?

    There are several ways in which a strut may fail or need replacement:
    • Most common is leakage. A small film of oil around the shaft is normally not a problem. Fluid covering several inches of the strut or dripping off indicates a need for replacement.
    • Noise, particularly on bumps, and coming from the strut is another problem indicating need for replacement. This should be carefully diagnosed, as good struts are replaced quite often due to mis-diagnosis of noise source complaints.
    • Ride quality is somewhat subjective but excessive bouncing and diving of the suspension is another symptom of worn struts.
    • Finally, struts are sometimes bent from pot holes, striking curbs or other impact to the wheel. This will affect wheel alignment and normally cause tire wear.

    For more information, please see our Detailed Topic, How Do You Know When You Need Shocks or Struts


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  141. What are the symptoms of a bent wheel?

    The most common symptom is vibration, much like an out of balance tire. This will continue even though the bent wheel may be balanced. Balance and being round are different factors. Other symptoms sometimes include losing air pressure, worn suspension components, scallop wear on the tire and/or noise when rolling.

    See our Detailed Topic Wheel Balance, Shimmy and Vibration for more information.


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  142. What are the symptoms of a tire with a broken belt?

    A broken belt will normally cause a vibration as the tire is no longer being held in a round condition. Often there may also be a wobble felt at low speeds and many times the vehicle may start to pull, if the tire is on the front. Inevitably the tire will fail, many times resulting in a blow out.
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  143. What are the symptoms of an out of balance tire?

    The leading symptom will be vibration when traveling at speed. Normally a shimmy in the steering wheel shows a front tire out of balance. A vibration in the entire vehicle is more likely a rear tire. Vibration from a wheel out of balance will normally come and go with vehicle speed. For instance a vibration at 45 MPH and not at 65 MPH or vice versa. Two clues of improper balance, when looking at the wheel are, no weights on one side or the other or more than one weight on either side. No weight can show static balance only or that the weights have come off. Multiple weights on one side of the wheel shows operator error.

    A new tire that was vibrating because of improper balance.


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  144. What are the symptoms of bad ball joints?

    Symptoms will vary depending on the type and severity of the failure. When the protective grease boots fail, grit and grime enter the joint. At this point symptoms may range from none to squeaks when turning and hitting bumps. As the wear progresses, slack develops and the wheel alignment will change. At this stage, tire wear, shimmy and slack in the steering may result. In the case of catastrophic failure the joint can pull apart and the wheel may separate from the control arm. This is extremely dangerous as we can lose control of the vehicle.

    See our Detailed Topic All About Ball Joints for more information.
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  145. What are the symptoms of bad tie rods?

    Symptoms can range from none at all to a shake in the steering wheel to tire wear. Improperly checking tie rods by squeezing them can also damage a good end. Proper inspection involves pushing in and out on the wheel while watching the joint for side to side movement.

    For more information, please see our Detailed Topic, Properly Checking Tie Rod Ends.


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  146. What causes cracks in the sidewall of tires?

    A leading cause of tire cracking is age. Many experts and vehicle makers state six-years is the maximum safe life of a tire. Please see our Detailed Topic article Old Tires With Good Tread for far more details.

    Use of tire dressing can also promote cracking of tires. Some tire dressing may remove the ozone protection from the rubber. Severe cracking at low age is usually a defect in the tire, a deficiency in manufacturing.

    Defective tire with severe cracking at after only three years age
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  147. What causes tire noise?

    Noisy is a pretty generic term. There are several different types of noise that tires may make and different causes for each noise. For instance a whining or singing type of noise is usually related to the tread pattern design. Engineers sometimes allow more noise to get other benefits. An example would be a mud-grip tire. All terrain tires are much noisier than a highway tread, but far better for off-road use.

    A thumping or slapping noise when rolling is often associated with an out of round tire. This is because the out of round tire bounces as it rolls. This may also cause a vibration and damage to the suspension. Please see our Detailed Topic Out of Round Tires for more information.

    A roaring noise, similar to a mud-grip tire or bearing type of noise is usually caused by tire wear, often called chopping. This is where the tread is worn is spots. The wear causes a rough surface, which can be felt with the hand. This wear can be caused by mis-alignment of the suspension, bent or worn parts or even a bad tire.

    Tire tread that has chopped wear.
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  148. What causes tires to make a roaring noise?

    Abnormal tire noise is normally caused by wear. Bent or loose parts, particularly on the rear, can cause tires to wear in spots. Often called chopping, such wear causes the tire to produce a mud-grip type roaring noise. A professional should be able to check the wheel alignment and identify the cause.

    Roaring tire caused by rear mis-alignment of vehicle.
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  149. What do the size numbers on my tire mean?

    Most passenger vehicle tires sold in the US employ the P-Metric size system. This is an alpha-numeric code which defines the tire size such as P255/60R17. The P means passenger use, the 255 is the width in millimeters at the widest point. The 60 is the aspect ratio and in this example means the tire sidewall is 60% as tall as the width. The R indicates radial construction and the 17 is the diameter of the wheel the tire is made to fit.

    There are also letters that indicate the "speed rating" which is how well the tire can resist centrifugal force. Load ratings which tell how much weight the tire can support, as well as a traction, temperature and wear rating. A maximum inflation rating will also be present.

    The number beginning with "DOT" indicates information identifying the tire with the last four digits indicating the week and year the tire was built. For instance if the last four digits of the DOT number are 2512, the tire was built in the twenty-fifth week of 2012.

    For more information on speed ratings, please see our Detailed Topic, Can I Substitute A Lower Speed Rated Tire.


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  150. What does air suspension mean?

    Air suspension is a system that replaces some or all of the conventional coil and torsion bar springs with springs that are supported by air. The advantage to air suspension is improved ride and the ability to adapt to varying weight loads. This allows the vehicle to better stay level, regardless of the load. Many vehicles use air suspension in the rear only and conventional suspension in the front. Others use air suspension on all four wheels.

    For more information please see our Detailed Topic Ford Air Suspension Problems.


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  151. What does it mean when a vehicle is said to be dog tracking?

    Dog tracking is often used to describe the front and rear wheels not traveling in line with each other. Many things can cause this, from poor wheel alignment to a bent chassis. When the moving vehicle is viewed from behind it appears to be moving sideways, sort of like a dog with its hind legs out of line with the fronts.

    For more information, please see our Detailed Topic, Wheel Alignment, Toe and Tracking.


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  152. What does negative camber mean?

    Camber is the angle of a tire, when viewed from straight ahead. If the tire stands straight, it is said to have zero camber. If the top of the tire leans toward the center of the vehicle, camber is said to be negative.

    For more information on camber and caster, please see our detailed topic Wheel alignment, camber and caster.


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  153. What does SAE 1205-1206 mean with regard to tire valve stems?

    SAE stands for Society of Automotive Engineers and 1205-1206 is their standard for ozone resistance in valve stems. These standards are extremely important but not well enforced. Millions of substandard valve stems have entered the US with disastrous results and a huge recall. The results were badly cracked and dry rotted valve stems in use. Unfortunately many tire dealers are ignorant of SAE 1205-1206. Asking if the valve stems being installed meet this standard may be a good way to judge the competence of a tire retailer.

    Please see our Detailed Topic Dangerous Valve Stems for more information.
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  154. What does the term separated mean with regard to a tire?

    A tire is said to be separated when air leaks between the plies of the tread. This results in a large bulge in the tread and very seriously weakens the tire. Symptoms of a separated tire include a wobble or waddle, especially when rolling at low speeds, under 30 MPH. The condition is very dangerous and complete tire failure very often follows, with little or no warning.

    A separated tire.
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  155. What does the term speed rating mean in regard to a tire?

    The term speed rating arises from the method used to test the structural integrity of tires. This is closely related to the amount of belting the tire has and the loads the tire can withstand, such as cornering and braking. Structural integrity of a tire design is tested by spinning at increasing speed, until centrifugal force tears the tire apart. Different speed ratings are assigned based on this data.

    Engineers design vehicle suspensions to load tires during braking, cornering and driving. If the vehicle is engineered for a specific rated tire and a lower rated tire is substituted, handling and safety can be effected. Problems can also appear with irregular wear and vibrations.

    For more information on speed ratings, please see our detailed topic, Can I Substitute A Lower Speed Rated Tire.


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  156. What does the term toe mean, with regard to wheel alignment?

    Toe is the relationship between the front of two tires, on the same axle, and the rear. For instance, if the distance between the front of the tires on the vehicle is the same as the distance between the rear of the same two tires, toe is said to be zero. If the front of the tires are closer together than the rear, the wheels are toed in.

    For more information, please see our Detailed Topic, Wheel Alignment, Toe and Tracking.


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  157. What does the term unibody mean?

    A unibody vehicle is one that uses structural components welded together, as a part of the body of the vehicle, rather than having a separate frame assembly. The rocker panels take the place of the frame rails and the front and rear aprons and body structure serve as mounting points for the suspension. By contrast, a frame type vehicle has a separate frame to mount suspension components and the body is supported by the frame. Some unibody vehicle also employ a partial bolt-in sub-frame for suspension mounting.
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  158. What does the term unidirectional tread mean with regards to a tire?

    Unidirectional tread has all of the main grooves in the tire facing in a single direction. The theory is, more water can be channeled from under the tire tread, on a wet road. A standard bidirectional tread has grooves facing in both directions. Care must be taken in mounting the unidirectional tire. The treads must face the proper direction in order to work and the direction is normally labeled on the sidewall of the tire.

    Unidirectional tread and mounting direction
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  159. What does TPMS mean?

    The acronym TPMS stands for tire pressure monitoring system. This is a system that monitors the pressure in the tires of the vehicle and sends a warning when they are out of a specified range. Most systems use wireless sensors located inside the tire. These sensors are often part of the valve stem assembly. There are also systems that monitor wheel speed through the ABS system. Since a low tire is shorter than a fully inflated tire, and rotates faster, wheel speed infers a low tire.

    For more information, please see our Detailed Topic Valve caps and TPMS.
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  160. What is a McPherson strut bearing and what symptoms do they normally give when bad?

    The strut bearing is the upper pivot point for the strut assembly. This is a small bearing that allows the spring to rotate smoothly when the wheels are turned. Symptoms often include a popping noise when turning or memory steer, a vehicle pull in the direction of the last hard turn.

    Parts of a typical McPherson strut
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  161. What is a steering damper?

    A steering damper is basically a shock absorber attached to the steering linkage. The purpose is to help prevent steering wheel shimmy by resisting the quick back and forth movement of the linkage. They are most often used on four-wheel drive vehicles, due to the larger tires presenting more opportunity for wheel shake.
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  162. What is a wheel lock?

    A wheel lock is a device, that normally replaces one of the regular lug nuts, on each wheel, and requires a key to remove. They are standard equipment on many vehicles and tend to slow a thief down. A number of tools are available to defeat wheel locks and these inevitably find their way into the hands of thieves; the locks are supposed to keep out. The most important thing is to be aware if the vehicle has them and to keep track of the key.

    For more information, please see our Detailed Topic, Wheel Locks.


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  163. What is an out of round tire?

    Out of round refers to the tread of the tire not being equidistance from the center point of the wheel opening, when measured around the circumference of the tire. When rotated, out of round causes the tire tread to move up and down.

    An out of round tire and a round tire compared
    The affect of an out of round tire is vibration and wear to suspension components. Out of round can be measured with a dial indicator against the tread of a rotating tire. In bad cases, out of round may be seen with the eye. Any amount over .030 of an inch (.762MM) is normally considered excessive.

    See our Detailed Topic Out of Round Tires for more information.
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  164. What is four-wheel alignment?

    Four-wheel alignment involves reading and adjusting alignment angles at each of the four wheels of the vehicle. Non-adjustable angles are read and compared to specifications. Four wheel alignment allows the front [steering] wheels to be referenced to the rear. Without this reference the front wheels may be aligned to one another but not the centerline of the vehicle.

    Not all vehicles are adjustable on all four wheels but the alignment should still be referenced and verified. On vehicles that are adjustable in the rear, rear wheels are adjusted first and then front wheels set in alignment to the rear. When the rear wheels are not adjustable, but are out of specifications, a problem is revealed. Such a problem should be diagnosed and corrected before alignment is attempted.

    For even more information on wheel alignment, please see our Detailed Topics article, Wheel Alignment Myths.
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  165. What is meant by match mounting a tire

    The concept of match mounting attempts to match the highest point on the tire with the lowest point on the wheel. Some believe this provides a more round assembly and thus a better ride. The procedure is time consuming and can add substantial cost to the price of tire mounting. A far better method is to correct wheels that are not straight and verify that tires are perfectly round before mounting.
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  166. What is the best tire air pressure gauge?

    Most gauges tested are not very accurate or worse do not repeat their reading consistently. The pencil or barrel type gauges seem to read better than the dial type, in my testing. The best gauge I have ever tested was the PCL Accura I digital gauge. Very simple to use, rugged and very accurate. We use them exclusively in our shop.
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  167. What is the difference between a strut and a shock absorber?

    The two terms are often used interchangeably today. Technically both are shock absorbers as they both serve to dampen suspension oscillations on jounce and rebound. Originally, a shock absorber dampened motion, but did not support load. Originally a strut typically supported a spring, served to dampen motion and support weight. Today there are multiple variations on both designs. Some manufacturers refer to one as a strut, another as a shock absorber and vice versa.

    Difference in a typical strut and shock absorber
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  168. What is the pressure required for a 245/75R16 tire?

    Tire pressure is not dictated by the size, rather by the design of the tire. For example, three 245/75R16 tires may each require a different pressure. For tips on setting the best tire pressure, please also see our Detailed Topic How To Set Tire Pressure for a great deal more information.


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  169. What makes some radial tires cause a vehicle to pull to the right or left when driving?

    The term for this problem is conicity. Perhaps an oversimplification, but the tire is slightly cone shaped, rather than flat across its tread surface.

    Exaggerated view of conicity in a tire

    As with any cone shaped object, the tire tends to roll in a circle, toward the shorter side. Conicity is normally cause by uneven distribution of belting under the tread. Alignment of the belts in the carcass is critical. If they are shifted, even a tiny amount, the tire tread will not inflate perfectly flat. If one side of the tread inflates slightly higher than the other, effectively a cone is formed, thus the pull.

    For more information on how a tire can cause a vehicle to pull right or left, please see our Detailed Topic Tire Conicity and Radial Pull.


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  170. What symptoms are present with worn tie rods?

    Most vehicles have the four tie rods, two inner and two outer on the front and sometimes on the rear. Tie rods connect the steering mechanism of the vehicle to the wheels. They also hold the wheels in position, relative to each other. When tie rods wear, the wear allows the wheels to toe in or toe out. Excess toe in or toe out causes tire wear. There may also be a loose feeling in the steering or a looseness when hitting bumps.

    Toe in and toe out in wheel alignment See our Detailed Topic Wheel Balance, Shimmy and Vibration for more information.
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  171. When are tires considered worn too much to use?

    Tires with remaining tread depth of 2/32 inch are normally considered legally worn out. Manufacturers normally cast small raised areas in the tread at this height. When the tread wears down and exposes the wear bars the tire should be replaced.

    Tire tread worn and wear bars showing.
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  172. When I use my truck for towing, the fan hits the fan shroud.

    The fan should be in the center of the shroud with the vehicle at idle. If so, engine movement would be the usual reason for the fan striking the shroud. Such movement is normally the result of broken or improperly attached motor mounts. When towing, the engine is loaded and rises up on the mounts. The movement can cause the fan to strike the fan shroud. If the fan is not in the center of the shroud at idle, possible frame damage might be suspected.
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  173. When replacing only two tires on a vehicle, should they be placed on the front or the rear?

    With only two new tires, the new tires should be placed on the rear. New tires provide greater traction and the vehicle will be more stable with the greatest traction in the rear. Slippage in the rear of a vehicle, at speed, will produce far more instability than slippage in the front. This is the case regardless of whether the vehicle is front or rear wheel drive. The affect is similar to a fork lift, turning the rear wheels to produce far more movement when steering.
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  174. When rotating tires, is it ok to cross and/or switch sides, or should you only rotate front to back same side? I heard switching sides can lead to belt damage due to opposite rotation.

    Switching sides when rotating will not damage a tire. This is a very persistent myth. Some tires are directional, and can not be switched for that reason. These will normally be clearly marked on the sidewall. Directional means the tread pattern is designed to work in a single direction. Most tires are bi-directional and it makes no difference where they are placed.

    I normally let the wear pattern dictate the rotation method. For instance, if the tires appear "chopped" or wearing in spots, I cross-rotate. If wear is very even, straight front to rear.

    See our Detailed Topic article Tire Rotation for far more details.
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  175. When should the struts on my vehicle be replaced?

    There are several ways in which a strut may fail or need replacement. Most common is leakage. A small film of oil around the shaft is normally not a problem. Fluid covering several inches of the strut or dripping off indicates a need for replacement.

    Noise, particularly on bumps, and coming from the strut is another problem indicating need for replacement. This should be carefully diagnosed, as good struts are replaced quite often due to mis-diagnosis of noise source complaints.

    Ride quality is somewhat subjective but excessive bouncing and diving of the suspension is another symptom of worn struts. Finally, struts are sometimes bent from pot holes, striking curbs or other impact to the wheel.

    Recommendations for strut replacement without the above symptoms should be viewed with scepticism. Strut replacement falls into a category that I feel is very often over sold.

    For more information, please see our Detailed Topic, How Do You Know When You Need Shocks or Struts


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  176. When should tires be replaced?

    From a standpoint of wear, when the tread is 2/32 of an inch at the lowest point. Tires may also require replacement much sooner, due to cuts or punctures that cannot be repaired. Separation of the tread and bulges in the sidewall will also require replacement, regardless of tread condition. Out of round tires, can cause a great deal of damage to suspension components and should be replaced for that reason.

    Dry rotted or tires with cracks in the tread or sidewalls should be replaced. Also, many experts and vehicle makers state, any tire over six years of age should be replaced, regardless of tread condition. See our Detailed Topic article Old Tires With Good Tread for far more details.
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  177. Where are Michelin tires made?

    Michelin builds tires in many parts of the world. About 80% of the tires we receive at AGCO Automotive are made in South Carolina, USA.
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  178. Why are cheap tires out of round?

    It does not automatically follow that cheap tires are out of round. I have seen very expensive tires that are out of round as well. Rushed production, the type of mold used, lack of quality in manufacture and many other factors produce out of round tires. From there, even a perfect tire can be ruined by improper mounting. Many of the factors that produce round tires have cost associated with them. This is why quality tires tend to be priced higher than low quality tires. All factors considered, quality inevitably cost less, even though the initial price may be more.
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  179. Why are vehicle manufacturers going to electric power steering?

    Electric steering has fewer parts, cost less to manufacture and uses less engine power. This offers a small savings in fuel mileage and allows the computer to control steering. Computer control of steering opens the way for features such as self parking vehicles. With electric vehicles it also allows for power steering without having to run a hydraulic system. On the down side, electric steering is more fragile than hydraulic power steering and may be more costly to diagnose and repair.
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  180. Why do some cars use air suspension?

    Air suspension improves ride, handling and control of wheel alignment by keeping the vehicle more level. It is generally used on high-end vehicles due to cost.

    For more information please see our Detailed Topic Ford Air Suspension Problems.


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  181. Why do some race cars fill their tires with nitrogen?

    Race cars are extremely concerned with tire pressure and not overly concerned with cost. One PSI may be considered significant in the handling of some of these vehicles. Nitrogen expands slightly less than air when heated. Since race car tires tend to build and loose heat very rapidly, it is hoped nitrogen will give slightly more consistent readings.

    For more information, please see our Detailed Topic Filling Tires With Nitrogen.
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  182. Why do the balance weights keep coming off of my wheels?

    Wheel weights come in a wide variety of shapes and clip styles. When weights come off, chances are the improper weight was used for the application.
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  183. Why do “V” rated tires cost more than “H” rated?

    To achieve a V rating, the tire requires more belting and higher quality construction than for an H rating.

    For more information on speed ratings, please see our detailed topic, Can I Substitute A Lower Speed Rated Tire.


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  184. Why is there an electrical connection on my power steering hose?

    Over the years manufacturers have used several types of switches and sensors on the steering. In earlier vehicles, the air conditioner compressor was disabled at full turn. This cut drag on the engine. Later vehicles sometimes use a steering sensor to increase idle speed when steering. Still others have variable power steering. This provides additional boost at low speeds to ease steering and less boost at higher speeds to increase steering feel.
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  185. Why would a tire that has no nails or punctures keep losing air pressure?

    Tires can leak in several places. Valve stems are one common place, particularly if the stem cap is missing. Another area of leakage is corrosion around the tire bead area of the wheel. This can leak a small amount in several places and be difficult to find. Leakage that occurs in new tires can be caused by a defect in the tire. Not common, but some tires leak through the rubber sidewalls. This is a defect and such a tire will often be replaced at no cost. Finally, wheels can sometimes have porosity and cause a leak. This is normally diagnosed by switching the tire to another wheel to see if the leak stays with the tire or moves with the wheel.
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  186. Why would my car still squeak after having it greased?

    Squeaking in a modern vehicle is normally a sign of a part failure. Bushings deteriorate, ball joints and tie rods wear in time. Properly greasing vehicles that can be greased can help prevent wear. Greasing a worn part is simply too little, too late.

    Please see our Detailed Topic All About Ball Joints for more information.


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  187. Why would my vehicle suddenly go out of alignment and start pulling hard to the right?

    Vehicles do not go out of alignment. All adjustments lock into place and in order for wheel alignment to change, something must bend, wear out or move. If the adjustments were not properly tightened during the last wheel alignment, something could have slipped out of place. Another possibility would be a tire has separated, which will cause a hard pull, even though the alignment is still okay. Moving the position of the tires, such as rotating, can reveal a tire causing a pull. Conicity, which is a defect in a tire will cause a pull to the right or left when driving and is often mistaken for a wheel alignment problem.

    For more information on how a tire can cause a vehicle to pull right or left, please see our Detailed Topic Tire Conicity and Radial Pull.


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  188. Why would putting shorter tires on my car make my speedometer read faster than I am actually going?

    Speedometers calculate vehicle speed based on drive axle speed and the circumference of the specified tire size. For each revolution of the axle it is assumed the vehicle travels a set distance. With a shorter tire the distance is less, so the speedometer will indicate a speed greater than actually traveled.

    To better see the effect, use the Tire Size Error Calculator. Enter the original tire size specified for the vehicle and another size being considered. The calculator will give the error of the speedometer in MPH between the two tires.


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  189. Why would the clunk noise in my Sierra Truck steering wheel keep coming back even though the intermediate steering shaft is well lubricated?

    Lubrication of the shaft is only part of the challenge. Because of the design, lubricant can actually attract grime which only causes more binding. This often wears the lower steering column bushing and the noise keeps returning. GM has released an updated shaft. Replacement of the shaft and replacement of the lower bushing offers a more long term fix.

    For more information please see our detailed topic GM Steering Column Clunk.


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  190. Why would the lug studs on my car continue to break? I know they were properly tightened to the specified torque.

    Lug breakage can often be traced to the wrong wheel or lug nut being used. The bolt pattern of many wheels are very close, but not the same. When the lugs are tightened, the studs will bend and eventually may break. Also using the improper nut for the type wheel will cause improper seating and breakage. Finally, if the center hole in the wheel is too small for the hub, the wheel will not seat properly and the studs may break.

    For more information, please see our Detailed Topic Wheel lugs, torque and keeping the wheels on.
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  191. Why would the lug studs on my car continue to break? I know they were properly tightened to the specified torque.

    Lug breakage can often be traced to the wrong wheel or lug nut being used. The bolt pattern of many wheels are very close, but not the same. When the lugs are tightened, the studs will bend and eventually may break. Also using the improper nut for the type wheel used will cause improper seating and breakage. If the center hole in the wheel is too small for the hub, the wheel will not seat properly and the studs may break. Finally, worn lug nuts may appear to tighten, but actually bottom out against the base of the stud. This will not hold the wheel tight and can cause the stud to fracture.

    For more information, please see our Detailed Topic Wheel lugs, torque and keeping the wheels on.
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  192. Will power steering fluid work in a vehicle that specifies automatic transmission fluid in the steering?

    Both fluids are similar in makeup, but have differences. Automatic transmission fluid or ATF has more detergents and may have friction modifiers, not present in power steering fluid. The viscosity is also different as well as other properties. There are no benefits and maybe problems interchanging the two.

    It is also important to note; ATF is not one thing. There are several types of ATF, and the proper type must be used. For example, there is Dexron III, Mercon V, Mercon SP, Toyota T-IV, Honda and many others. Always use only the fluid recommended and only the proper type.


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  193. Will putting load range E tires on my truck decrease my fuel milage compared with load C tires.

    If the vehicle specifies load E (10 ply tires) and they are kept properly inflated there should be no loss of fuel mileage. An under rated tire would more likely drop fuel mileage, because the load would effectively make it like an under-inflated tire. If load E tires are used and improperly inflated, there could be a loss of mileage, as with any under-inflated tire.
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  194. Will you explain tire dimensions?

    The P-metric system is the most common dimension rating. An example might be P265/70R17 91H. The P at the beginning means this is a passenger tire. The 265 is the width in millimeters, at the widest point of the tire. Slash 70 is the aspect ratio, which means the tire is 70% as tall as it is wide. The R indicates radial construction and 17 is the diameter, in inches, of the wheel. There are normally numbers and a letter following this. The number 91 above is the load rating for the tire and the H is the speed rating.

    Aspect ratio of a tire .

    For more information, please see our Detailed Topic, Can I Substitute A Lower Speed Rated Tire.


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  195. With no grease fittings on my vehicle, what can I do to prevent expensive suspension problems?

    By eliminating the grease fittings manufacturers actually extended the life of suspension parts greatly. Improper lubrication and contaminated lubricants contributed more to wear and tear than lack of lubrication. That said, proper lubrication (very rare) would have greatly extended the life, but that's another story. By a very wide margin, the single largest factor in suspension life is buying a quality round tire and having them mounted and balanced by a trained professional. This step alone can literally save thousands in repair over the life of the vehicle. The consequences of cheap tires, improperly mounted and balanced are far too expensive.

    See our Detailed Topic Ruining New Tires for more information.
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  196. Would a tire store be liable for an accident if they installed lower rated tires than recommended on my vehicle, and they fail?

    Only a court of law may decided liability, based on the circumstances. Improperly rated tires may change the handling and braking characteristics of a vehicle. This seems to me, a great risk for a tire store to assume, even with client insistence.

    For more information on speed ratings, please see our detailed topic, Can I Substitute A Lower Speed Rated Tire.


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  197. Would rotating my tires cause my car to pull to the right when driving?

    Rotating tires cannot cause the vehicle to pull, but can reveal a problem that causes a pull. For instance if the two rear tires have different tread patterns, different wear or one rear tire has ride disturbance, the vehicle may start to pull. Air pressure could be another concern if one rear tire was low. Different tire sizes can also cause a pull and will be less noticeable on the rear. The rotation did not cause the problem. Rotating the tires simply revealed a problem that was being masked by the tires being on the rear.

    For more information on how a tire can cause a vehicle to pull right or left, please see our Detailed Topic Tire Conicity and Radial Pull.


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