help with backspacing

4" is perfect, 4.5" with a spacer, and 3.5 " will work, but you will need to have the back end high and the wheel lips rolled all the way.
I think mine are 3.5 BS prostars. Ive ran 28x10x15 goodyear slicks and now 28x10.5x15 MT slicks on them without rubbing. No frame notch or fenders rolled. I do have airbags but I do not air them up a lot just to make them clear. Getting ready for Noble I assume?
yes I was going down last night but checked my rims and sure enough it was a no go.. I just bought 2 4" offs today so I will be there friday and sat.