8.25 rear backspace for 15x10 wheels?

Discussion in 'Tires and Wheels (Mopar Hubcaps Too)' started by QuickDart360, Nov 9, 2018.

  1. QuickDart360

    QuickDart360 Well-Known Member

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    Hey all! Looking to install 15x10 rear wheels in 1974 dodge dart sport. Want to know what backspace do I need to clear springs and if needed will trim inside quarter lip to make space for tires. I have the offset mopar shackles and spring hangers installed. Had to move spring pads/perches on rear and weld them on. So I think I have 3/4 " per side more clearance. Just not sure on backspace!
     
  2. QuickDart360

    QuickDart360 Well-Known Member

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    Saw some really cool 15x10 mopar rallys on summit and jegs. One set is 5" backspace the other is 5.5" backspace. Currently have a 15x7 with 4.5 backspace I think.
     
  3. 72bluNblu

    72bluNblu FABO Gold Member FABO Gold Member

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    The 8.25 is a little narrower than an A-body 8 3/4 with BBP axles. For a 10” wide rim with an 8.25 you’d want a backspace of about 5.25” to maximize the rear tire size with the offset springs.

    As for the quarter lip, it depends on how big of a tire you want to run. You can fit a 275/60/15 in there without cutting anything. Biggest tire you’ll actually fit inside the stock wheel well is a 295, and to do that you’ll probably have to trim the quarter lip all the back to the spot welds between the quarter and the outer wheel well. But that will depend on your car specifically, they’re all a little different and if you max everything out the body tolerances from one car to another make a difference. Same with the backspace, that should be close but always measure your own car before you start ordering parts.
     
    • Thanks! Thanks! x 1
    • QuickDart360

      QuickDart360 Well-Known Member

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      Actually my current wheel is 4.25 backspace not 4.5. And it comes kind of close in back to springs. So is backspace similiar as wheel width increases? That is the part that throws me off some!:eek:
       
    • diymirage

      diymirage HP@idle > hondaHP@redline

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      Nope, backspace is backspace, regardless of wheel width
      A 8 inch wide wheel with 4 inches of backspacing has exactly the same amount off backspacing as a 12 inch wide wheel with 4 inches of backspacing
       
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      • QuickDart360

        QuickDart360 Well-Known Member

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        I knid of figured that but was not certain on it!