Tire Size Calculator

This is a tire size calculator for the same or different rim sizes. It allows you to compare different tire and rim sizes and tells you the expected speedometer difference at any speed you pick. You can see the difference in diameter (in mm) and the sidewall height (in inches). Of course, there is no guarantee that the tires you’re looking at will fit your car or rims – you’ll have to check that out yourself. See the wheel / rim offset calculator to determine the best offset for your new rims.

When buying rims it is always advised to test mount the rims on the vehicle before mounting tires to ensure you have sufficient clearance to the fender and shocks/struts.

Enter the speed shown on the speedometer:

Current or original tire size
Section Width Profile Wheel Diameter Sidewall
(Inches)
Circumference (mm) % Difference Actual Speed Min Rim Width Max Rim Width
0%
Tire size you want to compare
Section Width Profile Wheel Diameter Sidewall
(Inches)
Circumference (mm) % Difference Actual Speed Min Rim Width Max Rim Width
%
%


Optimal Tire Size Calculator

This part of the calculator automatically figures out the best three alternatives for your tires based exclusively on the circumference of the tire. The minimum values are set and displayed for your information only, but you can adjust the maximum values so any tires found will be within the maximum width and profile that you specify. There is no gaurantee that the selections found in your rim size will fit your vehicle. This calculator relies on having values filled in for “Current or original tire size” above.

Minimum width to use: Maximum width to use:
Minimum profile to use: Maximum profile to use:
Pick the rim size you would like to use:
Rank Section Width Profile Wheel Diameter Sidewall
(Inches)
Circumference (mm) % Difference Actual Speed
1st
%
2nd
%
3rd
%

Check out all the calculators: