I have an 09 4x4 SCrew and am going to add a 2.5" AS leveling kit. I would like to upgrade the wheel/tire setup after doing this and have a few questions. If I upgrade to a 20x9 rim, what backspacing do I need to make the tires stick out about 1" farther than they do stock? What is the largest tire I can fit on this rim without doing any trimming after leveling it? Any imput is appreciated. Also, is there a difference between offset and backspacing?

 

A 9 inch wide wheel with 6 inches of backspacing would stick out 1 inch farther than your OEM wheels. However, I don't remember seeing many wheels with that spec (Moto Metal 951?). I think a 325/60-18 (33x13.00) would be as large as you could run with that wheel.