it's for my FC... i just put some rims on today and they are sticking out like 10-20mm more than the stock rims... would that be a bad idea? i mean if i happen to go over a big bump and the car would bounce hard, wouldn't the fender and the wheel hit?

and while i'm at it, if i were to put on some performance springs and shocks the car would be lowered a little bit right? then how bad would those rims be?

 

sounds like the wrong offset to me....get some fender flares

If you got new suspension, most likely it will be lower, and most likey closer to your fender, but then again, if you have stiffer springs/shocks, then there should be less travel in your suspension, but you probably would still have a problem.