Wheel Diameter Calculator

Total diameter

Total wheel diameter = rim diameter + 2 × sidewall height. Sidewall height = width × aspect ratio ÷ 100. Circumference = π × diameter. Every revolution travels one circumference.

• Circumference × wheel RPM = real road speed
• A larger tire = fewer revolutions per km = lower RPM at same speed
• A smaller tire = speedometer reads too high compared to GPS