How much backspacing with 42\" before contact? I'm right about to order my tires and I want to have as much backspacing as I can because I'm gonna be running 42" with a 6-inch lift and there is gonna be lots of trimming. My question is, how much backspacing can I have with 42" tires before the tires will start rubbing the leaf springs, steering box or anything else at full lock? Would 4.5" be too much? 4.75"?