Tire Size Calculator

Calculate metric or inch tire specs and compare to alternate tire sizes. View size results with our tire visualizer and side by side comparison including speedometer error using the comparison tab.

Use our tire size calculator to calculate the diameter, width, sidewall, circumference, and revolutions per mile of any tire. Just type in a metric or standard size tire and click calculate.

Inch measurement tires are fairly easy to understand however metric tires use a more difficult system to read. The first number on a metric tire is the width in millimeters. Divide this number by 25.4 to get the inch equivalent as there is 25.4 mm in 1 inch. The third number generally preceded by an “R” is the wheel diameter. The sidewall or aspect ratio are used in metric tire sizes to determine the overall height of a tire. The second number on a metric tire is to calculate the side wall measurement. The sidewall height is a percentage of the width of the tire. This second number is that percent. The sidewall height or “aspect ratio” of a 285/75/R16 tire is 75% of 285mm.

To calculate the diameter of a metric tire in inches: (#1 x #2 / 2540 x 2) + (#3)

Example: 285/75R16 (285 X 75 / 2540 x 2) + 16 = 32.8 inches tall.

Our tire calculator makes this happen for you. Just type in any tire size and click calculate. It also solves the problem of deciding what tire you would like to run if you have inch tire measurement in mind but can’t find a company that manufactures that inch tire size. Just fill in the inch measurements you are looking for and it will populate suggested tire sizes that are with in one inch bigger and smaller of the entered inch tire size. There are more possibilities and choices in metric tires so the use of a tire size calculator can be very useful.

The tire size comparison calculator takes the measurements of two tires and compares the diameter, width, sidewall, circumference, and revolutions per mile. Then as a bonus it shows examples of your speedometer reading with the first tire, and the actual speed you’re traveling if you were to install the second tire. A very useful tire calculator when searching for tires that are a different size than stock.

Another tire size calculator we have is our speedometer correction calculator. This is valuable if you plan to or are already running bigger tires than stock, and want to know the speed you are actually traveling compared to you’re speedometer reading. A bigger tire has a larger circumference, thus traveling a further distance for each revolution. A speedometer reads the amount of revolutions your tires are making, not how far you are traveling. Therefore you are actually traveling faster than your speedometer says when you have larger tires than stock, and slower than you’re speedometer says if you have smaller tires.

Our easy to use tire diameter calculators will always be useful at one time or another. A tire size conversion calculator or tire diameter calculator is the best way to get the answers you are looking for when it comes to tire sizes. What sets us apart is our tire suggestion guide. For each tire size you input our tire calculator suggests multiple tire sizes that are with in one inch bigger and smaller of the entered tire size. Select each link to see a list of tires that are manufactured in that size. Then by clicking on each tire you will be directed to our price comparison guide where we list a number of companies that sell each tire. Follow the price check buttons to view prices from each distributor. Making it as simple as possible to find the tire that is right for you at the best price.

Also browse our tire categories and deals pages for Jeep tires, 4X4 tires, cheap new tires, all weather tires, cheap truck tires, all season tires, and tires with free shipping.

Tire Size Calculator Charts by Wheel Size

Tire Size Calculator Charts by Diameter