Tom, from the definitions I've seen, if you lay a wheel on a flat surface, inside edge down, backspacing is effectively the distance from the mounting flange to the flat surface, but the bead seat is maybe 1/4"-1/2" above the flat surface. The wheel width is from bead seat to bead seat, sooo, the distance from center of the wheel to the flat surface (backspacing) would be half the width plus the 1/4"-1/2" lip,...A 6" wheel with a 1/4" lip has the centerline 3.25" above the flat surface; with a 3.25" backspacing the flange is lined up with the centerline for zero offset, right?
Oh well, what the hey...
