Quote:
Originally Posted by 996/699
For a 275/35 square set up on 2009 M3, why 18x10 et 25 over 18x9.5 et 22???
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The 18x10" ET25 wheel provides better sidewall support, especially for meaty tires like Hankook RS3's, Dunlop Star Specs, or R-compounds that already tend to run wider than normal street tires.
Using the 275/35/18 tire on the 18x9.5" ET22 wheel is a bit oversized, and due to the tires being ballooned with a narrower wheel, the tires effectively become ~270/35/18 since the tread is pulled in as the tire bead is pulled in. This happens when a tire is mounted on a wheel that is too narrow. Additionally, there would be less sidewall support from a wheel that is too narrow creating sloppier sidewalls, which in turn causes steering response to be less nimble and makes it more difficult to drive a tire at its limits. For street use this may not be an issue, but if one is looking for performance we do recommend the proper tire size and wheel width combination.