I have the 1.5" kit from Dr Diff w/ a B-body rear end, 285/40-R18 Nitto 555s, on cragar SS 18x10 aluminum wheels. I have all sorts of room left, easily 3/4 inch between leafs and wheel wells, some places closer to an inch. Only reason I went with 285s was I wanted Nitto 555s and they didnt make 295, 305, or 315s in the size I wanted... well at the time, they might now?