Red Pete - 9/7/2024 23:27
When I changed the speedometer in my truck I started with the numbers in the book and then fine tuned it by driving a known distance (highway markers). It took a few tries to get it where it needed to be. I think the ECM would need some reprogramming if you were changing tire circumference.
You're last line confuses me? The tabs on the back of the speedo are used to correct for tire size? | 
Peterbilt Speedometer Settings
