Tire Size Calculator
Calculate Tire Dimensions
Formula
Sidewall = Width_mm x Aspect / 100 / 25.4. Diameter = Rim + 2 x Sidewall. Circumference = pi x Diameter. Revs/Mile = 63,360 / Circumference.
Frequently Asked Questions
How do I read a tire size code?
A tire code like 225/45R17 means: 225mm width, 45% aspect ratio (sidewall is 45% of width), R for radial construction, and 17-inch rim diameter.
How is overall tire diameter calculated?
Overall diameter = rim diameter + 2 x sidewall height. Sidewall height = width (mm) x aspect ratio / 100 / 25.4 (to convert to inches).
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