rim backspacing

[sirjeremyjohnson]

I have a 85 Bronco 2 with a 2 inch coil spacer and block in the rear, Im thinking about getting some black steel procomps for my 31's i have now. Im wondering about the backspacing, I don't understand how I know which would be best, I think i want to go with a 15x8 inch wheel

 

[4x4junkie]

Backspacing is the distance from the inner edge of the wheel lip to the wheel's mounting surface (more backspacing tucks the wheels in closer to the vehicle, less makes them stick out of the fender more).

Most popular (by far) on a 15x8" wheel is 3.75" backspace (and is what I run on mine).