Useful Tools
After you enter your vehicles tire size (using either a measured tire height or entering your tires P-Metric information) plus your vehicles rear end ratio, this calculator will display a chart indicating the speedometer gear set combination needed for an accurate speedometer reading in your vehicle.

P-Metric (not required if you only know the overall diameter)
Section Width Aspect Ratio Rim Size
Overall diameter (not required if you only know the P-Metric measurements)
inches
Rear end ratio (in decimal format. EX: 3.73, 4.10, 3.42)