Tire Size Calculator

Calculate the overall diameter, circumference, and sidewall height from a metric tire size.

mm
%
in

Overall Diameter

26.7 in

周长84.0 in
Sidewall Height4.87 in
Revolutions Per Mile754

Overall Diameter vs Tire Width

查看公式 →

公式

## How to Read a Tire Size A tire marked 225/55R17 means: 225 mm width, 55% aspect ratio (sidewall height as % of width), R = radial, 17-inch rim. ### Formula **Sidewall = Width x Aspect Ratio / 100 (in mm)** **Overall Diameter = Rim Diameter + 2 x Sidewall (converted to inches)** **Circumference = Diameter x pi**

计算示例

Tire size 225/55R17.

  1. 01Sidewall = 225 x 55/100 = 123.75 mm = 4.87 in
  2. 02Overall diameter = 17 + 2 x 4.87 = 26.74 in
  3. 03Circumference = 26.74 x 3.1416 = 84.0 in
  4. 04Revolutions per mile = 63,360 / 84.0 = 754