Sunday, December 17, 2017 Detailed Auto Topics
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Several times a week folks come in for a wheel alignment. Their complaint is, the vehicle pulls to the left or right. Surprising, very often the wheel alignment is fine and the pull is actually being caused by the tires.

There are several reasons why a tire can make a vehicle pull to one side or the other

Unequal air pressure is common and easy to correct. As little as one PSI difference from side to side can cause a noticeable pull on some vehicles. The pressure must be equal side to side. This goes for the front as well as the rear. This requires an accurate gauge that will repeat its readings.

A low tire will make a vehicle pull

Another problem with a low tire is it can cause the vehicle to lean.  When the vehicle leans, the camber is changed.  Camber is the amount, in degrees, a tire leans in one direction or the other.  Camber will cause a pull toward the side with the most positive camber, other factors being equal.

In order to drive straight, the tires must also have the same tread pattern and very close to the same wear side to side. One front tire newer than the other is a very common cause of a vehicle pulling.

Coniciy in a tire cause the vehicle to pull when driven

Even new and matching tires commonly cause a vehicle to pull. Tire conicity is the term that describes this common defect. Many people will also use the terms ride disturbance or tire pull.

Tire conicity is caused by a tire that inflates to a slightly cone shape. Just as any cone will tend to roll in a circle, a tread pattern with conicity will cause the vehicle to pull to the right or left.

Conicity is a defect in a tire that causes a pull when driving

Tire conicity results when the belts in the tire were shifted slightly right or left when the tire was manufactured. This causes more belting on one side than the other. When the tire inflates, the side with the more belts will inflate less than the side with less, because it is stronger. This causes the cone shape that results in the pull when driving.

Separated tires, air leaks between the belts

Air can also leak from the air chamber, through the belts and cause the plies of the tire to separate. This will distort the tread area and cause the tire to pull. It is also extremely dangerous and unexpected tire failure can result. This often occurs when tires are improperly repaired after a flat. It can also happen due to manufacturing inadequacies.

An experienced alignment technician can sometimes spot a tire problem with a test drive. If the vehicle pulls harder as speed increases, a tire problem might be suspected. A tire pull may be barely noticeable at 25 MPH and quite pronounced at 60 MPH.

As a diagnostic procedure, the tires are temporarily swapped side to side and the vehicle is again driven. If the vehicle pulls the other way or quits pulling (sometimes) the tires must be corrected before alignment should be attempted. Aligning the vehicle with a tire problem is a waste of money and will not correct the problem.

Such defects are quite common in some tire brands. Such problems create other issues and cost the client time and money. AGCO has had excellent results with the Michelin brand of tires. Find out why we say, a Michelin tire, mounted and balanced by AGCO offers the overall lowest cost.





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