Tire Revolutions per Mile Calculator

How we calculate

Enter one tire size to calculate outside diameter, nominal rolling circumference, and revolutions per mile. Metric and flotation formats use the same geometry engine as our comparison calculator. The result table keeps inches and millimeters together so you can compare a tire specification written in either unit. Revolutions per mile describes how often the wheel turns over one mile in this ideal circular model.

How we calculate: metric diameter in millimeters is 25.4 times the rim diameter in inches plus two times the sidewall height. Sidewall height is width times aspect ratio divided by 100. For a flotation size, the first number is the nominal outside diameter in inches. Circumference equals pi times diameter. We divide 1,609,344 millimeters, exactly one mile, by that circumference to obtain nominal revolutions per mile.

A nominal 30-inch tire therefore has a circumference of about 94.25 inches and turns about 672.3 times per mile. A nominal 33-inch tire covers more distance in one turn, so its calculated revolutions per mile are lower. Keep the original inputs when comparing two results. Comparing an unloaded nominal value with a manufacturer's measured rolling value can otherwise look like a calculation error even when the definitions differ.

Rolling circumference here means the circular circumference derived from the size label. It is not measured under load. Actual travel per revolution depends on the tire's construction, tread depth, inflation pressure, temperature, operating load, and the measurement procedure. Manufacturers may publish tested revolutions per mile that differ from a simple pi-times-diameter calculation. Prefer their data when a calibration procedure calls for a measured specification.

This result can help explain the link between tire diameter, wheel rotation, and speedometer readings. It cannot determine a vehicle's allowable tire size, load rating, or clearance. If comparing tires for an all-wheel-drive vehicle, follow the vehicle maker's rules for matched rolling circumference and tread depth. Use the linked guides for the notation and comparison process, and discuss installation or calibration requirements with a qualified installer.

Frequently asked questions