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Thread: Does the gear ratio change as tire width changes?

  1. #1
    Tuner in Training
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    Dec 2015
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    Does the gear ratio change as tire width changes?

    I'm a newbie and read some writings that the gear ratio should change whenever the tire size changes.
    I actually found a site where they calculate your gear ratio so I used it and applied it on the Speedo menu.

    I just want to make sure what I did is right and I'm nt messing it up.

    Stock rear Tire & Gear Ratio = 285/35/19 , 3.23
    -> My new tires are 295/35/19 and changed the gear ratio to 3.26

    Does it seem right?

  2. #2
    Tuning Addict 5FDP's Avatar
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    May 2012
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    Rogers, MN
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    You don't change the actual rear end gear ratio when you swap tire sizes because you aren't actually changing the physical gears.

    You only change the tire size in the editor and use the auto scale feature to have the editor change the tables as it see's fit.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
    Tuner in Training
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    Dec 2015
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    23
    Thanks.

    So I have to go back to stock gear ratio which is 3.23?

    In this case, do I need to mod the trans tune?

    The tune was made based on gear ratio 3.23

  4. #4
    Tuning Addict 5FDP's Avatar
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    May 2012
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    Yes, put the stock rear end ratio back into the tune and just change your tire size in the gear/tire wizard. Then click auto scale and it will adjust for the tire size change for you. Anything past that for changes is up to you.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.