Quote:

Yes, they are 31's but why are you using the diameter?

The calulator I see wants MPH, RPM, Gear, & CIRCUMFERENCE (inches}



The calculator I am using works off diameter. Basically the calculator I am using takes the diameter, and uses the circumference based on the diameter.

31" X 3.1416 = 97.3896"

I have used this calculator to calculated quite a few cars and it has worked for me. I have had good luck with the Wallace stuff too though.