How it works

This advanced tire size and rim offset calculator utilizes exact geometric measurements to map out how an aftermarket wheel setup will sit on your vehicle.

When changing tire sizes, maintaining an overall diameter within 3% of the OEM specification is critical for the safety of your transmission and the accuracy of your speedometer. The offset (ET) and rim width calculations predict whether your new wheels will rub against the suspension struts or poke outside the legally permitted fender boundaries.