Decode a tire size like 225/45R17 into real world dimensions. The first number is the tread width in millimeters, the second is the aspect ratio as a percentage of that width for the sidewall height, and the last is the wheel diameter in inches. This calculator turns that code into the overall tire diameter, the sidewall height, the circumference, and how many times the tire turns per mile, all of which matter for speedometer accuracy, gearing, and clearance. It is essential when you are shopping for a new size, checking whether a plus size fits, or working out why a swapped set of tires changed how your car reads speed. Enter the three values and everything updates instantly. All calculations happen locally in your browser with nothing sent to a server.
The 225 is the width in millimeters, 45 is the aspect ratio as a percent of width for the sidewall, and 17 is the wheel diameter in inches.
It adds twice the sidewall height to the wheel diameter, where sidewall height is the width times the aspect ratio.
It is how many times the tire rotates over one mile, found from the tire circumference, and it affects speedometer and odometer readings.
Decode a tire size like 225/45R17 into real world dimensions. The first number is the tread width in millimeters, the second is the aspect ratio as a percentage of that width for the sidewall height, and the last is the wheel diameter in inches.
Yes. Tire Size Calculator is completely free, with no sign-up and no usage limits.
Yes. Tire Size Calculator runs in any modern web browser. There is nothing to download or install.
Yes. Tire Size Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.