I'm having problems getting my speedo calibrated since going to 35's. I know it's done through the ABS system and you have to change the revs per mile reading. I have tried several places, two independent(both using Snap-on scanners), and one dealer. No one can get into the ABS system to change the reading. I personally know the people that have tried so I know they aren't just blowing me off.
It's not a huge deal, but it bugs me. It's 7.5% off as per GPS.
The truck is a 00' F-250 7.3(obviously) Auto trans. 4x4