FWIW, I'm running a square set of 18x8.5 ET52 front & back, with 245/35R18 RE050A RFT tires all around.
10 mm spacers on all 4 rims (so the effective offset is 42 mm).
-2.2° negative camber up front.
No rub, no fender modifications... but it's very tight...
See
http://www.1addicts.com/forums/showthread.php?t=1170959
Karl.