Gear and Tire Calculator Free

Easy and versatile tool to calculate gear ratios in your drive train.

Easy and versatile tool to calculate many ratios of your drive train. Will calculate any ratio based on other fields. Handy for anyone wanting to re-gear their vehicles, change tire size, check rpm at a given speed (or speed at given rpm), etc. Both standard and metric measurements are supported. Includes large diameter tires. Feature requests are welcome.

Calculates:

Tire sizes

Differential ratios

Transmission ratios

Engine RPM

Speed