SBP Center Line Wheels

Standard backspace on 8 1/2 autodrags was either 3 5/16, or 4 7/8. If i were to make a guess, i'd say those were 3 5/16. The 4 7/8 versions are lots closer to the springs.
Edit: i have 8 1/2 autodrags on my car, with the 4 7/8 bs, and i have to use a 3/8 spacer to keep the tires from rubbing on the springs.