# Speedometer Calibration **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [August 30, 2008, 5:28pm UTC](https://community.cartalk.com/t/speedometer-calibration/18879 "2008-08-30T17:28:07Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![mhs112752](https://avatars.discourse-cdn.com/v4/letter/m/e9bcb4/32.png) [@mhs112752](https://community.cartalk.com/u/mhs112752)\ **Post date:** [August 30, 2008, 5:28pm UTC](https://community.cartalk.com/t/speedometer-calibration/18879/1 "2008-08-30T17:28:07Z")
I took my 2004 Avalanche into Woodland Hills Pontiac yesterday to have routine maintenance and asked that my speedometer be calibrated for my new larger wheels. I was told that it was unnecessary as the truck will automatically recalibrate, is that true or was I feed a line? ---
**Author:** ![BustedKnuckles](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bustedknuckles/32/25_2.png) [@BustedKnuckles](https://community.cartalk.com/u/BustedKnuckles)\ **Post date:** [August 30, 2008, 5:31pm UTC](https://community.cartalk.com/t/speedometer-calibration/18879/2 "2008-08-30T17:31:03Z")
Automatically calibrate? How? Does it have GPS integrated with the ECM? I smell major BS. ---
**Author:** ![edb1961](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/edb1961/32/122_2.png) [@edb1961](https://community.cartalk.com/u/edb1961)\ **Post date:** [August 30, 2008, 5:53pm UTC](https://community.cartalk.com/t/speedometer-calibration/18879/3 "2008-08-30T17:53:16Z")
If you got larger wheels and lower profile tires then the overall tire wheel diameter may not have changed, otherwise this sounds like baloney. I know that aftermarket programmers like Hypertech have the ability to account for changes in wheel/tire sizes and rear axle ratios. You could try checking the odometer using roadside mile markers. Ed B. ---
**Author:** ![oldschool](https://avatars.discourse-cdn.com/v4/letter/o/e19adc/32.png) [@oldschool](https://community.cartalk.com/u/oldschool)\ **Post date:** [August 30, 2008, 8:12pm UTC](https://community.cartalk.com/t/speedometer-calibration/18879/4 "2008-08-30T20:12:37Z")
As you were not asking for a free service why would the dealer turn down a oppourtunity to make some money?I know that thru the Tech 2 you have a range of tire sizes to select (range was not that great a most the original and 2 other very close options).Maybe GM made this a automatic feature as the years Iam refering to are late 90’s. ---
**Author:** ![FoDaddy](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/fodaddy/32/717_2.png) [@FoDaddy](https://community.cartalk.com/u/FoDaddy)\ **Post date:** [August 30, 2008, 10:02pm UTC](https://community.cartalk.com/t/speedometer-calibration/18879/5 "2008-08-30T22:02:10Z")
Why would you need larger wheels on an SUV? They’ll just get chewed up when you go off road. ---
**Author:** ![Joseph\_E\_Meehan](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/joseph_e_meehan/32/21_2.png) [@Joseph\_E\_Meehan](https://community.cartalk.com/u/Joseph_E_Meehan)\ **Post date:** [August 30, 2008, 10:13pm UTC](https://community.cartalk.com/t/speedometer-calibration/18879/6 "2008-08-30T22:13:45Z")
``` [b] Why would you need larger wheels on an SUV? They'll just get chewed up when you go off road. ``` [/b] How many SUV go off road other than when they miss the driveway after a night at the pub? ---
**Author:** ![FoDaddy](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/fodaddy/32/717_2.png) [@FoDaddy](https://community.cartalk.com/u/FoDaddy)\ **Post date:** [August 30, 2008, 11:57pm UTC](https://community.cartalk.com/t/speedometer-calibration/18879/7 "2008-08-30T23:57:47Z")
I know, I was being facetious. Obviously anyone who decides to get bigger wheels (18’s or better) on their SUV is an image-obsessed poseur. I’ve had people ask why I only have 15 inch wheels (but 33 inch tires) on my Bronco. Nobody understands that sidewall flex is a good thing when you’re not on pavement.