F-Body: 17x8 / 17x9.5 Backspacing

Chassis, Suspension and wheels

  1. 76B5

    76B5 Member

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    Looking for your advice on backspacing...

    I am looking to add a set of larger rims for an upcoming event (more on that later). It’s basically a 17” version of the wheel used on the Sam Posey Challenger. Here are my questions:

    a) will a 17x8 wheel with 4.5 backspacing work on the front?

    b) assuming no issues with a 17x8 wheel with 4.5 backspacing in the rear?

    c) will a 17x9.5 with 5.5 backspacing work in the rear?

    d) if I could have these made to order, what would be the ideal backspacing for a 17x8 in the front and a 17x9.5 in the rear?

    Thanks guys, really appreciate your thoughts.
     
    Last edited: Mar 14, 2019
  2. Duke5A

    Duke5A Well-Known Member

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    To my knowledge all F/J/M wheel well dimensions are the same.

    I'm running 18" on mine with I *THINK* 18x8 4.5" in the front, and 18x9 5" in the rear (I'm absolutely sure of the rim widths being right, only question the BS). If the above is correct and I think it is, a 255-45-18 tire rubs the torsion bar and K frame at full lock in the front and a 285-40-18 rubs a section of the wheel well in the rear when the suspension is heavily loaded. On the front I went with 245-40-18 instead and solved the rubbing issues.

    I can dig the information up tonight when I get home to know for sure.

    IMG_0404.jpg IMG_0401.jpg IMG_0395.jpg IMG_0405.jpg
     
    Last edited: Mar 14, 2019
  3. Opticon77

    Opticon77 Well-Known Member

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    ET LT-III "Minilites". I've been over these. Problem is if you fit a 17" wheel you won't have enough sidewall at stockish overall tire diameters. So you either end up doing something like Duke up there and running larger diameter tires to get some meat. But when you do THAT you have to stay skyjacked and run into rubbing on the inside up front -OR- Do like me and opt for 4" backspacing on 8" wide wheels to make a little room inside. But if you push the overall tire diameter in MY backspacing setup you'll be making bacon fenders. Maybe 4.25" backspacing is the magic number?

    Also note Sam Posey's Challenger has some fat rounded tires. You're not squeezing those under an F-body with a 17" wheel. In fact his are still probably only 15" on the E body.

    But if you stay with a low profile tire, 4-4.25" backspacing, and be ready to massage the wheel well lip. You can probably pull off a modern restomod look...

    f125eb7fcef3d58564f808272f5fcf22.jpg

    Careful of your tire choices. It's very hard to find a low profile tire with the proper muscle bubble sidewall. Most are flat sided as hell.

    Not sure about maxing the rear width. I kept my fitment square.
     
  4. 76B5

    76B5 Member

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    Appreciate the info and pictures guys. It’s looking like it’ll be 8” on all fours, just need to finalize backspacing.