Tire Size Calculator
Calculate tire diameter, sidewall height, rolling circumference and bike computer settings from wheel and tire size.
Hit Calculate to see your tire geometry
Calculate to compare against the selected reference
Metrics appear after calculation
Your explanation appears here
Real tires vary by brand, pressure, rim width and load. For cycle computers, a rollout measurement is the most accurate final calibration.
Your plan appears after calculation
Try another tire width or aspect ratio without changing your main result.
Calculate your baseline first
The calculator uses rim diameter × 25.4 + 2 × sidewall height. Sidewall height is tire width multiplied by aspect ratio. Circumference is diameter multiplied by π.
Most bike computers ask for wheel circumference in millimetres. Use the calculated circumference as a starting value, then fine tune with a measured rollout if precision matters.
Tire casing shape, pressure, tread, rim internal width and rider/vehicle load all affect real rolling radius. The result is a geometric estimate, not a physical measurement.
Results are estimates generated locally in your browser from standard tire geometry. They are for informational purposes only and do not guarantee vehicle, frame, fork, fender, brake, suspension or speedometer compatibility. Always verify clearance, load rating, speed rating and manufacturer recommendations before fitting tires. VisionVix accepts no liability for decisions based on this output.
