[chevyrestoguy]

I think a rim with a 4.0 or 4.25 backspace should get you what need. If your truck is air bagged, then the issue is more with outside edge of the wheeltub versus the vertical support strips. If you have plans to raise the bedfloor and move the wheeltubs up, then it will solve your clearance concerns. I think that's what DURG was trying to get convey.

Maybe a better way to solve this is to ask what rim width, backspace and tire size guys are running. If your rear axle is the stock one, then I think you can get your answer quickly. 5.25" is way too much backspace. Most of the new wheels (like Foose) are geared towards the late model cars that have wheel hubs very close to the edge of the fender lip. You can stuff a large tire under them, but it's all to the inside. The rims have little to no "dish" on the front side, and usually lots of backspace (sometimes 6" or more)