calculators
This calculator let's you do what-if scenarios using different tire sizes, axle ratios, transfer cases, and even the torque converter slippage on a C4 or C6.
Essentially there are two calculators - one to show you the engine RPM at your target MPH, and one to show you the vehicle MPH at a target engine RPM. To use them enter your info in the blue cells and see the results in the green cells.
The first variable you will need is Tire Diameter. The easy way to determine that is to have it calculated from the tire size on the sidewall by using the drop-downs. Or, you can go to Tire Rack and find the exact specs - assuming your tire is currently marketed. On the other hand you can go to Tire Size and check a generic tire size. Then enter that figure in the Tire Diameter cell.
Next, enter your Axle Ratio, the Target MPH at which you want the RPM, the Target RPM at which you want the MPH, the model transfer case you are using, and if you are checking on a C4 or C6 automatic the Slippage RPM for the torque converter.
Note that there are cells toward the bottom with transmission ratios, including one called "Other", and you can change the ratios for that transmission & enter your own, with the results showing up in the "Other" column in green. Also, if you question the ratios that are shown then you might want to check out the page on Transmission & Transfer Case Gear Ratios. The information there comes from Ford's yearly Facts Books that supplied the dealerships with all the latest information on these trucks.
Essentially there are two calculators - one to show you the engine RPM at your target MPH, and one to show you the vehicle MPH at a target engine RPM. To use them enter your info in the blue cells and see the results in the green cells.
The first variable you will need is Tire Diameter. The easy way to determine that is to have it calculated from the tire size on the sidewall by using the drop-downs. Or, you can go to Tire Rack and find the exact specs - assuming your tire is currently marketed. On the other hand you can go to Tire Size and check a generic tire size. Then enter that figure in the Tire Diameter cell.
Next, enter your Axle Ratio, the Target MPH at which you want the RPM, the Target RPM at which you want the MPH, the model transfer case you are using, and if you are checking on a C4 or C6 automatic the Slippage RPM for the torque converter.
Note that there are cells toward the bottom with transmission ratios, including one called "Other", and you can change the ratios for that transmission & enter your own, with the results showing up in the "Other" column in green. Also, if you question the ratios that are shown then you might want to check out the page on Transmission & Transfer Case Gear Ratios. The information there comes from Ford's yearly Facts Books that supplied the dealerships with all the latest information on these trucks.