Quote:
Originally Posted by shawnhayes
If you put them on the car, and mark where the tires are, and do 3-10 revolutions, if they are within 1% of the rotation (3.6 degrees) I feel pretty confident they'd be perfectly safe. You'd be shocked how much different 3.6 degrees x 10 rotations looks like. (Imagine 36 degrees of difference between the marks on the tires).
So, 1%, probably okay.
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BMW have used the 1% in the past. They are very vague these days in spelling out specific technical tolerances. They hang more on recommending their approved tires. Plus the details of tire exchange/rotation and tread depth tolerances.
As you say, the rolling difference can be quite different. The difference has to be absorbed somewhere. Either in transfer clutch slip (if not wide open) and/or tire scrub.