Formulas for Calculating Gear Ratios, RPM's, MPH and Tire Diameter

If you wish to do the math on your computer's calculator,

To multiply, use symbol *, to divide, use symbol /

GEAR RATIO = RPM * Tire Diameter / MPH * 336

RPM = MPH * Gear Ratio * 336 / Tire Diameter

MPH = RPM * Tire Diameter / Gear Ratio * 336

TIRE DIAMETER = MPH * Gear Ratio * 336 / RPM

From, Carl/Roseville