1. Welcome To GMTruckClub.com!

    The #1 Chevy Truck Forum Online
    Online since 2004, we are the #1 Chevy Truck & SUV forum and user community. If you have any questions about your Chevy or GMC Truck, SUV or Crossover, or just want to connect with other GM owners and enthusiasts around the world, you've found the best place on the internet to do that.

    Join Today ~ It's Free
    Registering is Free and Easy! Hope to see you on the forums soon!

Larger tires and speedometer/odometer variation

Discussion in 'General Chevy & GM Tech Questions' started by Boxman7481, Oct 22, 2009.

  1. Boxman7481

    Boxman7481 Member

    With larger than stock tires installed on my Colorado the speedometer is 4-5 MPG less than actual at speeds of 65-75 MPG (checked with GPS).

    How does this affect the odometer? Am I putting more miles on my truck than actual??
  2. daweinah

    daweinah Rockstar 100 Posts

    Hmm, your wheels have a larger circumference, so they are traveling further per every rotation of the wheel, so I think your odometer would actually read less?

    EDIT: So yes, if your wheel circumference got 10% longer, you will have traveled 110 miles when your odometer says you've been 100. Would probably throw off your DIC readings too. Wonder if that can be adjusted..?
    Last edited: Oct 23, 2009
  3. Thundare

    Thundare Rockstar 100 Posts

    Yes this can be done by changing the gear in i think the transfer case to match the size of your new tires.
  4. XS ive

    XS ive Rockstar 100 Posts

    I believe you can also modify the ECU to compensate for larger tires by changing shift points as well as speedo/odo readings??
  5. canislupis69

    canislupis69 Epic Member 5+ Years ROTM Winner 5000 Posts

    You can adjust for the tire size (and gear size if you ever change gears) with a hand held tuner. I used a hand held tuner to adjust my speedo for my 35 inch tires and my gear change from 3.73 to 4.56. I used a garmin and kept adjusting with the hand held until my speed was dialed in perfect.

Share This Page