Tire Size Calculator

Bike tire sizing can be confusing because three different systems are in common use: ETRTO (international standard), French (for example 700×25c), and inch labels (for example 29×2.3″). The ETRTO system is the most precise because it uses tire width and bead seat diameter in millimeters, so 700×25c is 25-622 and 29×2.3 is 58-622.

Knowing your exact wheel dimensions is critical for speedometer calibration, tire clearance checks, gear ratio calculations, and ensuring rim compatibility. Our calculator instantly converts between all three systems and provides the total outer diameter and circumference for any tire and rim combination.