Tire Size Comparison Calculator

Compare diameter, width, circumference, revolutions per mile, and indicated-versus-actual speed for two tire sizes.

Original tire

New tire

Speedometer reading

—Diameter change

—Width change

—Actual speed

—Rev/mile change

—Geometry only. A dimension comparison does not confirm vehicle clearance, load rating, wheel compatibility, or safe fitment.

How to use this Tire Size Comparison Calculator

Compare two tire sizes side by side and estimate dimensional and speedometer differences. Enter your values above and the result is calculated directly in your browser. No account is required.

Fast answer, clear inputs

This tool is built around one job: give the answer quickly without forcing a signup or hiding the result. Related tools are linked nearby when the next calculation or conversion is useful.