Can anyone explain once and forall the pros and cons of various wheel sizes? Am I right in my assumption that the only real reason to run 18" or 19" wheels is to fit big brakes behind them? And maybe a +1 or +2 wheel is obviously going to be wider and thus more rubber on the road? I'm not terribly concerned with how "cool" my wheels look, I'm more after performance. I'm thinking of perhaps a lightweight 17x8 wheel for the street, and maybe even 15x8 Kosei K1s on my E30 M3... they look decent and they're only 13 lbs. Are there any real performance benefits of going to the bigger wheels? Thanks for your insights while I try to make up my mind on what wheels to get.