Before my motor swap my car speedo would be approx. 71-2 and the scanmaster said it was only running 70. After my motor swap which i pulled the tranny with too the speedo says i am doing almost 75 when the scanmaster says i am doing 70. What could make them get so far off? My car does have 18 inch rims and tires but i had them before i did the motor and tranny and i had it reprogrammed for the new rims and tires.

 

hmmmm. that's rather odd. this may be a long shot, but, could your tires have lost some pressure??

or, maybe your pcm needs to be readjusted.