When selecting a Gear Ratio, you should consider the following:
1. Tire Size2. Transmission Ratio
3. Final Gear Ratio
4. Engine RPM at Cruise Speed
The following formula has been developed to calculate the optimum final Gear Ratio to suit your application.
M.P.H. X Gear Ratio
Tire Diameter X 336 = rpm____________________
The chart shows RPM calculations at 55 MPH for various combination’s of final Gear Ratio
and Tire Diameter.
According to this chart, the acceptable RPM range is 2000-3000 which is represented by the entire shaded
area of the chart. The optimum RPM range is 2300-2600, and it is represented by the tan shading. When changing ratios to improve mileage, choose a ratio within the yellow shaded band above the optimum range. When changing ratios to improve power, choose a ratio within the orange shaded band below the optimum range.