Wheel Diameter Calculator
Calculate total wheel diameter, circumference and distance per revolution, then compare two tire sizes to see the difference in speedometer and ground clearance.
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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
FAQ
Half of the diameter difference. Going from 205/55 R16 to 225/45 R17 changes the diameter by about 4 mm, so the car sits about 2 mm higher or lower.
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