Tire Size Calculator

Overall diameter from a metric tire size like 225/45R17. Sidewall width is in mm; rim diameter is in inches (industry standard).

Tire Size Calculator helps you overall diameter from a metric tire size like 225/45R17. Sidewall width is in mm; rim diameter is in inches (industry standard). Enter section width, aspect ratio, and rim diameter, review the breakdown, and use the guidance below to understand what the number means — and what it does not. What the Tire Size calculator does Tire Size Calculator is built for everyday questions — shopping, home, travel, hobbies, and tech. Overall diameter from a metric tire size like 225/45R17. Sidewall width is in mm; rim diameter is in inches (industry standard). You enter section width, aspect ratio, and rim diameter, then Simple Calculators computes the result instantly. Defaults are chosen to be easy to read — change any field to match your situation. How the math works Enter the Section width (mm), Aspect ratio (%) and Rim diameter (inches) from the code, for example 225/45R17, and choose how to Show diameter in. Sidewall height = width × aspect ratio ÷ 100. Overall diameter = 2 × sidewall + rim diameter (1 inch = 25.4 mm), circumference = π × diameter, and revolutions per mile or km follow from that. It assumes a new, unloaded tire. The formula: Diameter = 2 × (w…