Tire Diameter Calculator

Overall tire diameter in inches and mm from any tire size, plus sidewall height.

Formula

Diameter = (Rim diameter × 25,4) + 2 × (Tire width × Aspect ratio (%) / 100)

Assumptions

Overall tire diameter in inches and mm from any tire size, plus sidewall height.

How to read it

Overall diameter combines the rim (in inches) and two sidewalls (width × aspect ratio). Fitments on different rim sizes can share the same diameter — this figure, not the rim size, drives speedometer and ride height.

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