56mm off set = inches?
SPANKY LS1, the numbers you posted would be the backspacing measurement on the respective rim sizes. However, your math is correct.
01WS6vert, a +56 mm offset is a +2.2047244072 inch offset.
To determine backspacing, you would add 1/2 of the rim width to the backspacing in inches....
[rim width/2]+[mm offset x 0.0393700787]
You're right though, the offset, by itself, has nothing to do with the width of the rim.
Shawn 


