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Old 10-01-2009, 12:40 PM
Supercourse Supercourse is offline
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Originally Posted by vrooom3440 View Post
Very likely for different width/profile tires to have different rolling circumference.
Good point.

I haven't done the calculation, because I have never been interested in owning a vehicle with different size tires front to rear.
(Unless there was a real performance advantage, rather than looks.)

But I would imagine that BMW carefully selects the tire sizes in a "staggered" set-up so that the rolling circumference difference is very small.
Or tune the X-drive dynamics to compensate.

Given that a new tire has about 10mm. tread depth, I would think that the rolling circumference difference between old and new tires in a standard set-up is more of a concern.

But another factor is that the 2 pairs of tires (old and new) would also have very different road-holding ability on wet roads, for example.
X-drive would have to handle that on a constant basis - not really the intended purpose.
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