I have a 98 M3/4. I plan on lowering it with H&R Sport springs. I know the correct size for an 18x8 wheel is either 225/40/18 or 235/35/18, but what about 235/40/18. Is it that much taller? The 235/35/18s are expensive and the 225/40/18s are to narrow, for my liking. What if I roll the fenders? Thanks.