Offset vs. backspacing

Discussion in 'Fiesta ST Wheel and Tire Upgrades' started by Smokin, Jul 17, 2014.

  1. Smokin

    Smokin Active Member

    Help me figure this out. What's the difference between offset and backspacing? Which number moves the wheel/tire in or out from the strut?
  2. Register or Sign in

    Advertisement Sponsor

  3. iLiptiKal

    iLiptiKal Active Member

  4. IIRC, et is the positive (toward the outside) or negative distance from the C/L of the wheel's rim to the flange face of the wheel's spider. Back space is the measurement from the back lip of the rim to the flange face of the wheel's spider. Back space is typically a positive number, et can be a positive or negative number.
    Last edited: Jul 17, 2014
  5. Dyn085

    Dyn085 Active Member

    Smokin likes this.
  6. jimclark

    jimclark Active Member

    The video was pretty clear, and helped assure me that I was correct in assessing the inside v. the outside of the wheel in the diagram above.

    I now think of backspace simply as the depth from the mounting face of the wheel to the inside rim. Offset is the distance of the mounting face from the centerline of the wheel--that is, the distance that the mounting face is offset from the wheel's centerline. If the mounting face is moved from centerline to the outside, it is positive offset (and gives a greater backspace), and if it is moved to the inside, it is a negative offset, and the backspace is reduced.
    Last edited: Aug 6, 2014
  7. Smokin

    Smokin Active Member

    I like pictures.
  8. OrangeFist

    OrangeFist Member

    ok, so does that mean a higher offset number mean the wheel sticks out more?
    sorry if its a dumb question:confused:
  9. JustinP

    JustinP Member

    Other way around, smaller number for offset, wheel sticks out further. In truck applications, you'll Alot of times have negative numbers.
    OrangeFist and jimclark like this.
  10. OrangeFist

    OrangeFist Member

    Thank you!

Share This Page