Dealer won't change tire size in OBD

[Rob H 88]

Just put a slightly larger tire on my 1500 BTS edition and speedo is off by as much as 5 mph. Went to the dealer to have them input the correct tire size and was told the truck automatically senses tire size and auto adjusts speedo. Said only time they manually adjust is w 40 inch tires. Need a new dealer.

 

[Dean2]

Yes you do!!. However, my suggestion, get an MX+, Koadatech security cable and download AlphaOBD. For the same price as the dealer making that one change you now have the ability to do a whole lot more, including the inflation limits on your TPMS system.

I would have happily paid the dealer to fix the Fog light drop out, adjust TPMs limits etc but despite having a great Dealer, there is stuff they just can't access. They are locked out by Stellantis. That was actually what convinced me to get the AlphaOBD.

 

[turkeybird56]

Just put a slightly larger tire on my 1500 BTS edition and speedo is off by as much as 5 mph. Went to the dealer to have them input the correct tire size and was told the truck automatically senses tire size and auto adjusts speedo. Said only time they manually adjust is w 40 inch tires. Need a new dealer.

Yeah U probably do need a new dealer.

 

[Quick_Shifter]

Only trucks with factory gps can automatically calibrate tire size but there are still limitations. But the dealer didn’t completely lie

 

[Rob H 88]

Well if that's true and I have no reason to doubt you, then that seems to be a terrible flaw in the design as many truck owners change their tire sizes and by not providing a means to correct that would throw thousands of speedometer s off.

 

[crash68]

@Rob H 88 there is also Tazer DT if you don't to go the AlfaOBD route.

Tazer DT – Z Automotive

www.zautomotive.com

 

[John Jensen]

It's amazing what customers are told. Usually the "dealer" is a salesperson or a Service Advisor. I wouldn't believe anything those people say.

 

[Rob H 88]

True, I totally agree and that's why I called later to talk to the service manager who came from Ford and admitted he didn't know much about Ram yet but conferred with his coworker who supposedly knew a lot about Ram and basically just gave me a run around with no solution. Newdealer here I come