This is a gear ratio calculator designed to help our customers decide on the best transmission and differential choice for their purposes. If you're curious how changing ratios will affect your gearing, this tool will remove the guesswork.
Note that it includes three BMW transmissions that will eventually be available for both K series and stock BP powered Miatas. These parts are currently not in production, but you can read about them here. Be sure to subscribe to our newsletter so you're notified of updates.
Also note that GM Getrag diff ratios are included with the Miata ratios. These can be installed with a Getrag diff upgrade kit from V8 Roadsters.
|Tire Width (mm):|
|Tire Aspect Ratio:|
|Wheel Size (inches):|
|Engine Redline RPM:|
|Cruising Speed (MPH):|