Tire Sidewall Calculator

Convert a metric tire width and aspect ratio into sidewall height in millimeters and inches.

Section width (mm)

Aspect ratio (%)

—Sidewall mm

—Sidewall inches

—Two sidewalls

—Sidewall / width

—Sidewall height = section width × aspect ratio ÷ 100.

Tire geometry & size comparison

The sidewall inputs above remain primary. Add the wheel diameter to calculate overall tire geometry and compare another tire size.

Wheel diameter (in)Compare tire sizeIndicated speed (mph)

—Current size

—Overall diameter

—Circumference

—Revolutions

—Diameter difference

—Actual speed estimate

Ready.

What the aspect ratio means

The aspect ratio is sidewall height as a percentage of nominal section width. A 265/70 tire therefore has a theoretical sidewall height of 70% of 265 mm. Actual mounted dimensions vary by rim width, pressure and manufacturer, so the result is a sizing estimate.