Tire Size Calculator
Decode those confusing tire size numbers into real dimensions. Enter the three numbers from your tire size (like 225/45R17) to calculate overall diameter, sidewall height, circumference, and revolutions per mile. Use this to compare alternative tire sizes.
Tire sizes follow the format: Width/AspectRatio R WheelDiameter
- Width (mm): The tire's cross-section width
- Aspect Ratio (%): Sidewall height as a percentage of width
- R: Radial construction
- Wheel Diameter (inches): The wheel rim size
So a 225/45R17 tire is 225mm wide, with a sidewall that is 45% of 225mm (101.25mm), mounted on a 17-inch wheel.
Tip: When changing tire sizes, keep the overall diameter within 3% of the original to avoid speedometer inaccuracy and clearance issues.