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Thread: Smaller Tires - Rear Drive Ratio

  1. #1
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    Smaller Tires - Rear Drive Ratio

    I bought a set of 2007-2009 Shelby GT500 wheels. The rear tires are Goodyear Eagle F1 285/40-18. Diameter is 27". I have 4.10's now. Is there a way to determine the new rear drive ratio? The speedometer is now about 5 mph slow. My Marauder wheels have the Nitto NT555 265/50-18 which has a tire height of 28.4"

  2. #2
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    Wallace racing has every calculator you would ever want
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  3. #3
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    The difference in wheel size is 5%. The RAR is going to be affected according.
    .

  4. #4
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    Adjust the tire revs on the tuner, use tire size calculator.com


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  5. #5
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    Smaller Tires - Rear Drive Ratio

    4.31


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  6. #6
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    Thanks guys.

    I'm just going to run these for Auto Cross events, so I'm not worried about the speedo.

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