Calibrate your Speedo and Tach

[redbone3]

Calibrating Speedometer and Tachometer

How to calibrate your speedometer and tachometer:

Speedometer: compare with a GPS. Or, you can use the GPS app on a I phone.

Tachometer: Go to this site: http://www.precisionsite.com/auto-x/tools/
Put in the information for your car and you can compare your tach reading to the speedometer reading. The calculator assumes you have stock wheels and tires. Uncheck the (Fudge) box.

 

[CR94]

On vehicles old enough to have a mechanically driven odometer, and manual transmission, you can check tachometer using only a stopwatch, if you know all the relevant gear ratios between engine and odometer. That method does not depend on tire size or actual road speed at all.

 

[MasterSolenoid]

OP, I'm more old school.

Aren't the Mile Markers along the Thruway every 1/10 mile ?
Using the Markers and a Stop Watch could be used.