how exactly are the wheels rubbing, are they rubbing on the upper portion of the rear wheel wells, or are they rubbing on the front when you turn? i have heard that on the e36 models the m3s have the rear wheel wells factory rolled so that they can fit larger wheels, so i figure that this would be the same with the e46 m3s. on the idea of 18 inch rims im pretty sure that they won't rub at all. no matter what you go with the 18 inch rims will be a smoother ride because you have more tire to cushion bumps and imperfections in the road than the 19 inch rims do.
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