[special-K]

I don't know, but I've never gotten into the whole modern wheel thing. Wheels used to all have a backspace that would allow any wheel with the same bolt pattern to fit a vehicle with the same bolt pattern. When buying wheels you just got the diameter and width you wanted and unless you measured for your own curiosity, you never knew the backspace. From that standpoint and through all those years, to me "offset" equates to what we referred to as "dish", the opposite of backspace, the depth to center on the front, which would be the balance of the backspace figure when subtracted from the width. You could do the math if you really needed to know what those figures equated to in what you refer to as "offset", but I don't know why that would matter. I've never run across any cases of wheel offset not being the balance of the width after subtracting the backspace. Do you have an example?