All you'll need to know are transmission gear ratios, differential gear ratio, and tire diameter. Always measure tire diameter with the tires at proper inflation and mounted on the car, because ...

Correcting the gear ratio for compatibility with tire size allows engine speed to return to the proper rpm range and the transmission into the correct gear for the speed being traveled (like stock).

Read more about gear and final drive ratios and how to calculate these figures using Excel in Sport Compact Car magazine.