ok i picked a dana 60 for my gmc 4x4 but i want to run 15 inch rims i have bought a pair of bart racing wheels 15x12 8 lugs with 3.5 backspacing my question is how much do i have grind so nothing rubs? and for the people saying why dont you use a bigger rim no i have the tires and if i stick with a 15 inch rims i have more tires brands and style to choose from then other sizes.