Tire Diameter Increase MPH Accuracy

[Dlguzz]

When I increase the tire diameter by approx 1" from stock, the speedometer will be incorrect by almost 3%. Can the dealer correct for this via the OBD for me?

 

[Tremper126]

Yes. You can also look into android/ pc software called Alfaobd and do it yourself for under 100$

 

[Dlguzz]

Great. Thanks!

 

[carlhenry]

the dealer can also do it but dont know what they charge

 

[Dlguzz]

Thanks! I did a little follow up and it seems FCA has made it pretty tough to DIY on the last couple model years. The dealer charges $120 for the "license" from FCA and $80 for the programming labor. Seems a bit of a racket to me but I guess when my truck and wheels all arrive, I'll get if figured out.

 

[Tremper126]

What year is your truck?

 

[Dlguzz]

2021, Bighorn, Ecodiesel. I'm ordering wheels/tires and the truck is on a train somewhere in the Midwest heading to Idaho.

 

[Tremper126]

Hell yeah! Not sure how new ones have a work around but I believe you have to bypass power gate module on 17 and newer ones to be able to access anything

 

[Dlguzz]

Thanks Tremper! I guess I'll see what happens in a couple more weeks.