It really depends on the design of the rims especially the spokes. I have +33 at the front and it didn't clear the calipers. Had to put in a real thin spacer. 2-3mm to clear them. The rears are usually not a problem.
i am at the middle of filling the Check list for Works P1 Flash... by http://www.workevo.com .. here is something i donno... i hope sifu here can help me :D