Dealer recalibrate speedometer for bigger tires?

sailor9908 · October 4, 2015

They can and if they say why can't then you can have them install a hypertech speedometer calibration programmer and do it yourself and keep your warranty intact

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Ryan698 · October 5, 2015

They can and if they say why can't then you can have them install a hypertech speedometer calibration programmer and do it yourself and keep your warranty intact

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My dealer said they have to install the hypertech in order to keep your warranty.

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Ryan698 · October 5, 2015

Also getting it put in, in roughly 30 mins

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ViLo · April 30, 2019

On 7/28/2015 at 10:54 PM, Hunter79 said:

I recently just added a 6 in lift kit and 35 in tires. I was wondering if the dealer could recalibrate the spedometer so I don't have to use an after market tuner and ruin the warranty I payed extra for on the computers. I know how to calculate what speed i'm going just not how off the odometer is going to be. Those are the two questions I am concerned with and as always all replies are greatly appreciated.

I own a 2010 Basic Silverado,

I went from the regular stock 17's to a 265/70/18

The difference is 5 miles.

How do I know?

When I use the Waze GPS app, the app shows the speed at 75, and the speedometer shows 70.

I did try my Ford Ranger and my wife's CRV and Waze is accurate.

I can manage so if the speed limit is 70, I'll drive 65, but it is annoying

3tspapat · May 1, 2019

It’s not always off by 5 miles. It’s off by a percentage so the actual miles off will vary with speed. Just happens to be 5 miles off at 70 mph.

camcamaro1991 · May 1, 2019

Holy old thread!

I can program via GM's SPS here at home, I can in for a fact verify GM does NOT update tire size with a calibration or tune for tires, its all based on outside tire diameter infact there is always room for it being off just a little bit, to be more broad spectrum for 18's vs 20's vs 22" as they are not exactly the same but similar enough. Programming is all based on VIN number (unless you are referring to Chris White & MVI custom programming which is not GM's dealer SPS tool, and a closely guarded secret ) however with some control modules there is the ability for deviate like adding rear camera for for the HMI etc. however for gearing and tire size anyone that says its possible with GM dealership SPS software is wrong, for Custom build trucks with big tires the dealer is more than likely using HP Tuners or other 3rd party software like OBD2 canned tuner handheld, or the diablo!

Just do you self a favor and pickup HP Tuners and learn yourself, it will open your eyes up. Been using HP Tuners for over 10+ years now, how you guys dont buy is beyond my understanding, its super nice diag... and scanner tool even if you don't tune vehicles. if you want to program at home via SPS, I also recommend the VCX nano programmer w/ SPS subscription 2 years for 1 VIN for $40 (separate cost from the tuner & a good working laptop windows 10 64 bit here and works fine). and they include tech 2 and GDS2 software with the programmer. I have updated a few control modules on my 2016 Truck & 09 V, it works great with TECH 2 and GDS2 for diag... BCM, HVAC, anything the dealer can do.

As a former tech for MB, I worked along side the best and worst techs, most I would not let change the oil in my push mower. Its pretty hard to find good honest techs. I will do everything I can to do it myself at home.

Edited May 2, 2019 by camcamaro1991

Michael Lennon · January 4, 2020

On 7/28/2015 at 10:54 PM, Hunter79 said:

I recently just added a 6 in lift kit and 35 in tires. I was wondering if the dealer could recalibrate the spedometer so I don't have to use an after market tuner and ruin the warranty I payed extra for on the computers. I know how to calculate what speed i'm going just not how off the odometer is going to be. Those are the two questions I am concerned with and as always all replies are greatly appreciated.

Google TIRE SIZE CALCULATOR and you will find a page that will answer all your questions. No joke. It will even give you your true speed when you plug the numbers into the boxes.