tire diameter, circumference, speed difference and rotation calculators
Compare tire sizes with transparent geometry
Calculate sidewall height, overall diameter, circumference and simple speedometer-difference scenarios from tire-size inputs.
Tools
Tools
Sidewall Height
Calculate sidewall height from tire width and aspect ratio.
Open →ToolsOverall Tire Diameter
Estimate overall diameter from sidewall and wheel diameter.
Open →ToolsTire Circumference
Estimate circumference from overall diameter.
Open →ToolsDiameter Change
Calculate percentage change between original and new overall diameter.
Open →ToolsIndicated vs Actual Speed Estimate
Estimate actual speed from diameter ratio.
Open →Guides
Guides
Understand the common tire-size dimensions
Width, aspect ratio and wheel diameter describe different parts of the assembly.
GuidesOverall diameter combines wheel and two sidewalls
The tire adds one sidewall above and one below the wheel.
GuidesDiameter changes can affect speed indication
A larger rolling circumference travels farther per revolution.
GuidesUse tire math as a comparison tool
Geometry does not determine whether a tire is suitable for a vehicle.