FR 500 18"x 10 with +40 offset
From what I understand, if you have the rim for it, you can go as large as 345's in the rear. 345/35r18. However, I also recall reading somewhere on this forum, that rubbing at the bumpstop, if you go that wide and lowered, can present itself. I can't explain it myself, but the writer of it did make sense.