Visual RPM, Speed, and Gear Ratio Calculator 

This program allows you to interactively change the variables that determine your engine's RPM at any given MPH between 0 and 250. You can alter the axle gear ratio, transmission gear ratio, tire height or profile, torque converter efficiency, and see the impact in realtime.
For example, you may wish to know what effect that 4.10 ring and pinion will have on highway cruising speed before you buy it. Or, maybe your speedo is inaccurate and you'd like to know how fast you're really going when the tachometer is at 3,000. All the transmission and axle ratio fields are dynamic so you can customize them for your car. Drag the floating panels around if they get in your way. 

Notes:


The formula used for determining RPM given MPH, axle gear ratio, transmission gear ratio, and tire size is the following: mph X 336.1524 X final drive ratio ÷ tire diameter Or, the unsimplified long version: mph X 12 (inches per foot) X 5280 (feet per mile) X axle gear ratio X transmission gear ratio 

Source code for this project is available for 