Here's a handy link to help calculate the diameter of the tire you should buy based on your speed, differential gear ratio and RPM.

Simply enter three of the 4 fields, then click "calculate" on the field you want the answer to.

Tire diameter, gear ratio, speed and RPM calculator

~~ Darcy

1959 GMC 9310 Canadian- built Shortbox Fleetside Deluxe
FootStomper
In the Stovebolt Gallery
In the Project Journals Forum