Calibrate Speedometer
 

Trying to calibrate my speedo for the new tires and im not sure its doing anything. I adjusted the revs per mile to what the new tires are and my GPS is still showing 4-5 mph higher than speedometer. Original tires revs per mile was 649 i think and my new tires are 579...
Any advice would be much appreciated.

I know this is a very old post, but the Anti-lock Brake Module controls the speedometer. The Vehicle Speed Sensor's first stop is the ABS module where the AC sine wave from the variable reluctance output is converted to a digital signal read by numerous modules in the vehicle.

Certain scan tools have the ability to reset the revs/mile in the ABS module as the PCM has nothing to do with it.