How to Use

This calculator helps you find the overall diameter of your tire. Look at the sidewall of your tire for a number like 225/75/R17. Here's what each part means:

• 225 = Tire width in millimeters
• 75 = Aspect ratio — this is the sidewall height as a percentage of the width (i.e., 75% of 225mm)
• R17 = Wheel diameter in inches

Enter each of these numbers into the boxes and click Calculate. Use this tool for tires you currently have or ones you're considering.