8.5 +37 on front I'm not so sure. This post on is300.net has some useful info and pics... 19 x 8.5 +45 front, 19 x 9.5 +45 rear. With +37 you'll be 8mm further out than the IS in these pics....
http://www.is300.net/forums/showthread.php?t=210167
Compared to standard http://toy4two.home.mindspring.com/offset.html, standard is 7 +45mm, 8.5 +37mm. Over current settings this will be 11mm less clearance on inside (fine), 27mm less on outside - not so sure about this, 27mm is a lot on the front.