An out of round tire is one that the tread of the tire does not rotate in a true circle around the axis of the tire. Instead the tread rises and falls when rotated, much like rolling an egg end over end.
Three leading causes of out of round tires
Manufacturing - Many tire are simply made out of round. This is a particular problem with cheap tires. The type of mold used in manufacturing has a good deal to do with how round the tires produced will be. Segmented molds generally produce much rounder tires. They are also substantially more expensive to use, adding to the price of the tire.
Mounting - A perfectly round tire can be quickly destroyed by improper mounting. Please read our Detailed Topics Article, Ruining New Tires for far more details.
Mis-diagnosis - Some tires are referred to as out of round but actually have totally different issues. An improperly balanced tire may be perfectly round and still shake. A bent wheel will make any tire mounted on it appear to be out of round. A separated tire will also cause a violent shake and is very dangerous. Separation and out of round are totally different issues.
With tire separation, part of the outer tread cap has separated from the body of the tire. Tire failure quickly follows, often with catastrophic results. Tire separation is very dangerous and can result from under-inflation, manufacturing defects and impacts.
Avoiding out of round tires can be a matter of selection Selecting a quality tire is the only choice. Tires are one of the most important pieces of safety equipment on the vehicle. Cheap tires simply cost way too much when you consider the damage they can do to your vehicle.
Selecting the proper shop to mount and balance your new tires is as important as buying a quality tire. Realizing quality mounting, balancing and service is part of the tire cost can help in the tire buying decision.
We feel the more you know, the more likely you will choose AGCO. A great tire, mounted and balanced perfectly and great follow up service. AGCO, overall lowest cost, it’s the way to go.