Rim size to speedo calibration.
 

Does anyone know the math to figure out the following?

Have 18" rims now and speedo is pretty much accurate.

If I put on 19" rims will it make the speedo read higher then actual speed being driven or will it register slower then actual spped being driven?

The miles driven will explain themselves with the answer to the above question.

If register faster then spped traviling then miles will show more. If slower then miles will show as less.

Right?

Joe

Rim size alone will not cause the speedometer to be different than actual speed. The outer diameter of the tire will be the determining factor. You can use the calculator at this site (paspeedo.com/calculator.htm) to determine what effect various sizes of wheel/tire combinations will have on the accuracy of your speedometer and odometer.
John

Much Thanks...

The 1010 tires website also has a very nice calculator with illustrations etc...