Speed recalibration

jsumner83 · February 20

I have a 2017 Sierra 1500 5.3 4x4. I just picked up the truck today after getting 4.56 gears installed. I noticed my speed on the dash is about 15mph faster than my actual speed, according to the speed app I was using. How do I get this recalibrated?

Edited February 20 by jsumner83

rav3 · February 20

YouTube has several videos on this.

steelerdude15 · February 20

If you know someone with HP tuners, they can recalibrate it for you without having to purchase credits.

CamGTP · February 21

If said person has never tuned is truck before, they must purchase credits to tune it.

HP Tuners is never free to change tire size on GM vehicles.

steelerdude15 · February 21

16 hours ago, CamGTP said:

If said person has never tuned is truck before, they must purchase credits to tune it.

HP Tuners is never free to change tire size on GM vehicles.

My bad. I though you could.

MikeBMW · February 27

Yep, gear changes will need a professional tuner application.
I do have "professional" tuner devices such as the FlashPaq (which is very good, IMO - it's a Holley branded tuner) which mainly correct for tire size.
I could be mistaken, however, as I've never performed a gear ratio change.
My Autel MaxiSys can, also correct for tire sizes but I bought that after I bought the FlashPaq. Not sure about gear ratio changes (see above.)

Edited February 27 by MikeBMW