Offset / Backspacing ?

Discussion in 'Classic Mustang Specific Tech' started by imshaggy2000, Dec 11, 2003.

  1. Just a simple question. What is the difference between offset and backspacing on a wheel. I assume they measure the same thing just in different ways. Is offset measured from the "offset" of the center of the wheel? example a 17 x 9 wheel with a 24mm offset (aprox 1") would have 4.5"(center)+1"(offset) resulting in a wheel with 5.5" backspacing? Is this right or am I way off?

    BTW: Off topic but I can't see any of the pics on stangnet anymore, not even by just clicking the links of attached files. Does anyone know whats going on all i see is the latemodel mustang stangnet logo?
  2. You are close....

    In your 17x9 wheel example, the 9" measurement is inside the beads. A 9" wide wheel will actually measure about 10" in width from outside lip to outside lip.

    Offset is measured from the centerline, backspace is measured from the outside wheel lip - a 17x9 wheel with +24mm/1" offset would actually have about 6" of backspace. Positive offset means the mounting surface is further toward the outside of the wheel - negative offset gives the "deep dish" look.

    Here's an excellent link that describes all this, with the added clarity of PICTURES! :nice: