Originally Posted by CombatNinja
Firstly, the OEM M3 tire sizes are wrong. You would need 225/35 or 235/35R19 up front and 255/30 or 265/30 in the rear. The stock M3 rubber is too tall and will only exacerbate the fact that the rear fitment is just too aggressive. Remember that the M3 has flared wheel arches for a reason. Not sure on the exact offset but I'm pretty sure that the M3 Comp. Pack rears are 9.5 wide with a offset of 23. That puts them 27mm farther out in the rear than your stock wheels, which is quite a bit! You can get away with it if you run the correct sized tires and roll the rear fenders. Otherwise you will be rubbing tire on fender on big bumps particularly if you have passengers. The front fitment is straightforward. Another possible solution is to have a competent shop machine the mounting face of the rears down 8 to 10mm to bring the offset up. The last solution is to fit some Avant Garde type 359 wheels which are pretty much exact copies but with offsets more friendly to non-M cars.
I was wondering the same. Thanks