What do tire size numbers mean?

In 225/65R17: 225 is width in mm, 65 is aspect ratio (sidewall height as % of width), R means radial, and 17 is wheel diameter in inches.

What is tire circumference used for?

Tire circumference determines how far your vehicle travels with each tire rotation. It's essential for accurate speedometer calibration and odometer readings.

Why do I need to know revolutions per mile?

Revolutions per mile/km helps understand tire performance and is used in speedometer calibration. It varies based on tire size, affecting your vehicle's actual speed vs displayed speed.

Tire Size Calculator

Overview

Calculate tire dimensions, diameter, circumference, and revolutions per mile/km from tire size specifications.

The Tire Size Calculator helps you understand tire specifications by calculating key dimensions from width, aspect ratio, and wheel diameter. Get tire diameter, circumference, section height, and revolutions per mile/kilometer for any tire size.

How to use

Calculate tire dimensions in a few simple steps.

Enter tire width: Input the tire width in millimeters (e.g., 225).
Enter aspect ratio: Input the aspect ratio as a percentage (e.g., 65).
Enter wheel diameter: Input the wheel diameter in inches (e.g., 17).
View tire specifications: Review calculated tire diameter, circumference, and other dimensions.

FAQs

What do tire size numbers mean?: In 225/65R17: 225 is width in mm, 65 is aspect ratio (sidewall height as % of width), R means radial, and 17 is wheel diameter in inches.
What is tire circumference used for?: Tire circumference determines how far your vehicle travels with each tire rotation. It's essential for accurate speedometer calibration and odometer readings.
Why do I need to know revolutions per mile?: Revolutions per mile/km helps understand tire performance and is used in speedometer calibration. It varies based on tire size, affecting your vehicle's actual speed vs displayed speed.