fender tuck

I have 18's 5 Zigen and Tenzo Coils with just enough tuck to get half of the tire in.

only time i have a problem is doing a hard turn.. it sometimes hit the back chasis.

if you get rid of your splash guards you will not have a problem with the fender unless you have a super wide tire.

another thing you have to do is roll the inside of your fender using your hand.. just bend up all that metal thats sticking out when you take off the splash guard.

as for speed.. you will notice gas mileage will get worst and the car will be heavier going up hills.. if you dont mind that.. go for it