[hbmike]

for performance and handling purposes, would it be better to keep the same size tire all the way around, i.e. 235/40/18, or do you get better handling out of the staggered setup?

i would think you get a little more understeer with the staggered setup, and would choose to do the staggered setup on a non-m more for looks....

am i mistaken? :dunno:

 

[rvnvet]

I'm pretty sure you are correct about the understeer but the 255's in the rear will really fill out those 8.5 wheels nicely. If your car is lowered you might have a rubbing problem in the rear since BMW recommends the use of 255's on stock sport suspension. I have 18x8.5" Breytons with 225x40's on them and the tires are a little too small for the 8.5' wheel. When they wear out I'm going with 235x40's all around with AVS ES100's...