Tire Diameter and wheel fitment - Front/Back

Discussion in 'Suspension, Steering, Brake & Wheel Topics' started by 8pack, Jun 4, 2017.

  1. StrongSurvivor

    StrongSurvivor Member

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    How much clearance between the rear tire and spring / wheelwell?
     
  2. StrongSurvivor

    StrongSurvivor Member

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    Hi Everyone,
    First, apologies if I appear to hijack this thread, believe me that is not my intent. Second, thanks to all for the info. I've gone through the wheel/tire sticky's and learned alot, though I still have a question or twelve! Using the calculator, it looks like I "should" be able to run a 28x12x15 MT Sportsman S/R on a 15x10 Weld Draglite w/ 5.5" BS on the back of my '81 Z28 without interference. The tire has a 12.1" section width and the wheel has 0 offset, so from wheel mounting face on the drum to the inside tire sidewall is 6.05", with the same dimension to the outside sidewall.

    So, is anyone running this wheel and tire combo on the back of their Camaro? Any problems with clearance?

    Regards,
    MarkB...
     
  3. gray86hatch

    gray86hatch Member

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    The tire to spring is 1/2
     
  4. 8pack

    8pack Veteran Member Lifetime Gold Member

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    Just to stay on topic...

    I have done quite a bit of searching online here and can't seem to get any good info on this issue/Question.

    The stock tire size and Diameter is 235/60/15 and 26.1"
    Section width = 9.5"
    Backspacing 4.5"
    The rear end is offset about 1/4" to passenger side which sounds normal.
    My Suspension Measurements:
    Front - TBD

    Rear Driver -
    • Tire sidewall to spring 1 7/8"
    • Tire Sidewall to spring clamp 1 11/16"
    • Wheel lip to spring 2 7/8"
    • Wheel lip to spring clamp 2 5/8"
    Rear Passenger -
    • Tire sidewall to spring 1 7/8"
    • Tire Sidewall to spring clamp 1 5/8"
    • Wheel lip to spring 2 5/8"
    • Wheel lip to spring clamp 2 3/8"
    I am going to go with 18" wheels out back and 17" out front. From what I can see I should go with an 18" wheel with 5.5" Backspace for the rear and 17" with 5.0 BS for the front. Open to other suggestions.

    The tire sizes are a bit confusing as the Section width and tire height seem to be the most critical measures for clearance but sidewall height is important to keep the tire proportions looking right. I am assuming I can and probably have to run a slightly larger than stock tire height in the rear to get everything in proportion. Here are tire size options with comments below:

    Front:

    255/45/17 - 17x8.5"
    Tire diameter = 26"
    Sidewall height = 114MM
    Section Width = 10.2"

    Rear:

    Option 1: 285/40/18 - 18x10
    Tire Diameter = 26.96
    Sidewall Height = 114MM
    Section Width = 11.4"

    Option 2: 275/40/18 - 18x9.5
    Tire Diameter = 26.65
    Sidewall Height = 110MM
    Section Width = 10.9"

    I am trying to figure out how to measure how much the tire moves in closer to the spring when considering the added backspace and section width.

    When looking at the sidewall on the 275 compared to up front on the 275 the sidewall is 4MM smaller which might make it look silly with a skinnier sidewall in the rear. The total tire is around .5" taller.

    On the 285 the sidewall height matches the front and it is 1" taller, but the section width is almost 2" wider than the stock. In general, the 285 might be a tighter fit and I am having a hard time figuring out how to verify if it will fit.

    Looking for as much perspective and feedback as I can get. Thanks!!
     
  5. 8pack

    8pack Veteran Member Lifetime Gold Member

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    Assuming your tires have the same section width as what I have noted above, 10.9" then going to the 285 would add a 1/2" to the section width, 11.4" with the 285 tire and only leave me a 1/4" based on the 1/2" clearance you have....

    I need to measure the distance to the fender edge I think to see what would happen on the outside of the tire...

    Am I figuring this right and does that leave enough room for tire deflection under load in turns?
     
  6. gray86hatch

    gray86hatch Member

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    I would go no wider than 275
     

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