Quote:
Originally Posted by DM7
Tire wear will affect your speedometer reading as well. Going from a brand new tire with 9/32" tread depth to a bald one with 2/32" multiplied by 2 is 7/16" of change in diameter. Speedometer indicated speed will be higher than actual speed. Going from one tire make and model to another will change diameter as well even if they have the same size specifications.
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Tire wear/tire size, etc will effect actual speed, but has no effect on
indicated speed.
The speedo is actually a tachometer reading the RPM of the output shaft of the tranny. Any changes from the tranny on back will not have any bearing on what is indicated on the speedo.
You could mount a pair of 20s on the drive wheels, or a pair of 10" tires on the drive wheels...the speedo will still read the same relative to engine RPM.