I have a 95 4x4 with a 4" suspension lift. I want to run 32x11.50x15 procomp mud terrains on 15x8 procomp steel wheels. First, is a 15x8 right for a 11.5 wide tire and second, what back spacing do I need so that they wont rub; options are 2.5", 4RS, 3.75 or 4.5. Thanks