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Duramax speedometer calibration

I have a 2011 Duramax. I changed the tire size from the 245's to 285's and took my truck to the dealer to get the speedometer calibrated. GM said that my engine and transmission combination did not support this tire size and would not give the dealer the calibration code. Does anyone know a way around this to get my speedometer calibrated.
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2 Replies
Senior Contributor

Re: Duramax speedometer calibration

Check on of the aftermarket 4x4 dealers. Or a better GM dealer. Some around hear are selling new trucks with lots if aftermarket stuff. Even lift kits and much bigger tires than you are talking about. Plus the metric number you gave is mm of width. If you stay with the same % sidewall it will change speed but if you went from 245/85/16 to 285/70/16 you may not have changes diameter enough to worry about.
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Re: Duramax speedometer calibration

I can't remember my tire size but was told by two dealers that I was at the top end of calibration limits on my pickup.  I simply used  a

Garmin for aperiod of time and can be very close on speed just by adjusting now.  Maybe not completely honest but my pickup will display less miles when I trade it offSmiley Happy

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