I'm running TE37SLs with Federal RS-RR 215/40 on 17x7.5 +40 (non-concave) and 275/35 on 18x10 +40 (concave) which tends to be more conservative than aggressive but did not require any fender modification. I'm pretty sure you can run a 215/40 with a 17x8.5 +40 (non-concave) and 18x10 +40 as-is as well. AFAIK, SLs don't get concave until you use a 17x9 +22 but that's aggressive for the front and will require some combination of fender modification, stretched tire, and negative camber (similar work if you're going to use the 18x10.5 +22 in the rear).