Computer changes - for Wheel decrease from 20" - 17's

[john_johnson]

I have a 2015 Express. Does anybody know, is it possible for the Dealership to re-program the speedo/odo from 20" down to 17" inch rims ? I called them, but they said I would have to pay 70$ for them to plug in odb - they said going bigger is for sure, but going smaller is up in the air. Has anyone changed their speedo ?
One guy told me that the computer would even self fix itself after a month. What is true? What is possible?

Thanks!

 

[chrisbh17]

You would have to compare the outer diameter of your tires, 20" to 17"

If you stayed with stock sizes on the 20" and 17" wheels, the outer diameter is basically the same IIRC, so the speedo would need very little (or maybe even NO) adjustment.

 

[john_johnson]

My purpose is to go smaller on tire size, thats why I want rid of the 20" rims. I also am getting a 2/4 lowering kit - so I can get in the truck without a ladder. I love the truck but want it to be the height of the good old days trucks - drives me crazy that Im 6 foot tall and can't reach into the bed of the truck. So I was going to go lower profile tires on 17 rims also

 

[chrisbh17]

Take a look over in the AlfaOBD thread, we can reprogram for tire sizes but you need a bluetooth OBD interface, the AlfaOBD app (android or windows only) and the RF hub PIN from your dealer.

The setup is more than the 70 your dealer is asking, but for all we know they will charge you 70 to say they cant do it

AlfaOBD thread - https://www.ramforum.com/threads/alfaobd.123982/

 

[Redheadhunter21]

No PIN number needed for tire size change. And its all about tire height not rim size