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  1. #1

    Default Tire Diameter and fuel data

    Have a 2005 Chevy Suburban 3/4, 4x4, 8.1L. C ame with 245-75-r16 tires. I came across a good buy on some 265-75-r16 tires. I know they will alter my mechanical speedometer reading but what about the driver data provided by the computer such as: mpg and miles remaining until empty? Will they mess that up to?
    If so, how can I restore its accuracy and still use the larger tires?

  2. #2
    Legend Mean_Green_95's Avatar
    Join Date
    Apr 2009
    Baton Rouge, Louisiana, United States


    you will have to get a hand held programmer and change the tire diameter that is set in the computer.
    2010 Equinox LT
    2.4, 6 speed auto, power lift gate, remote start, bluetooth, xm.

    1995 Cheyenne C1500 ext. cab(my baby, my first truck)
    5.0, 5 speed, Silverado appearance package, power nothing, bucket seats and console Silverado, painted black interior, eBay halo headlights, eBay chrome tails, eBay cai, dual Flowmaster 40's w/no cats, 15x7 American Racing Hopsters, Walmart fog lights, SS mirrors

  3. #3


    Actually the newer the vehicle, the more things which rely on vehicle speed and the speed of the tires.

    Like a factory radio stereo will increase the volume with the speed of the vehicle.

    NAV units use this for keeping track of where you are in tunnels or where no GPS signals can be received.

    ABS uses differences in tire speeds for diagnostics and when to apply brakes.

    Of course speedometer/odometer.

    Traction control uses this information to determine if a wheel is slipping.

    The engine computer uses this information along with the computer controlling the transmission.
    92 GMC Sierra 2500

  4. #4
    Legend tlperry68's Avatar
    Join Date
    Oct 2008
    Huntington Beach, CA


    I've talked about this to the dealer with my truck. I put on 285 / 75 / 18 and I was told they had to flash the computer. After they looked into it there is no current GM "computer code language" for the year truck I have. So my computer still thinks I have the stock tires on. Now it says I get 13.5 MPG but I know its off a bit, I sould be around 16 to 18 for the average.
    Trevor - Huntington Beach, CA
    2007 GMC 2500 4X4

  5. #5


    its not a big difference, i wouldn't worry about it, i made that switch on my truck, and the speedometer says 60 and im going 62, so its not worth it to me

  6. #6

    Default 265-75-16s

    My speedo was off by 2 mph and still got 21 mpg on the interstate after installing 265-75-16s mudders on my 98 4x4 surburban.

  7. #7

    Cool tire Diameter and fuel data

    The stock ecm will adjust up to 10% increase in the size. The factory understands some people change to a slightly larger tire so the built this into there ecm programs.

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