Quote:
Originally Posted by freebeard
....... Is roundness an actual thing? . Don't they shave tires to concentricity? .......
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The actual term is *Uniformity*, which is more than just roundness. It's also variation in stiffness.
So, Yes! It is a thing. Vehicle manufacturers specify the type and amount of each type of uniformity they allow - and usually the specs are pretty tight. The tire manufacturers have machines in their factories that measure uniformity. There are 2 types of machines: Tire Uniformity Graders (TUG's) and Tire Uniformity Optimizers (TUO's) The TUO's have a grinding mechanism that will reduce the amount of uniformity in addition to their measuring capability. BTW, these types of machines are in the million dollar range - per machine, and a tire factory will have dozens of them.
So, Yes! They do *shave* tires, but it's a bit more sophisticated that just shaving for roundness.
If you look up Hunter GSP9700, you'll find a shop level machine that closely resembles the more expensive TUG's, but is much smaller and less expensive, but doesn't have the capability of correcting uniformity - except by reorienting the tire on the wheel.