Understanding Tire Codes

Written by Lee Wyatt (last updated May 15, 2012)

If you have ever looked at the side of a tire before then chances are you have noticed (at least in passing) that there are some letters and numbers grouped together in some kind of order. Well, that group of numbers and letters is actually an alphanumeric code that has been mandated by the International Organization for Standardization (ISO) to allow people to know the specifications of a tire with relative ease, regardless of the language used. Understanding tire codes is rather simple as long as you know the secret. To help make the process a little easier, use this code (which could easily be found on any car) as an example:

P215/65R15 95H

  • Vehicle class. In our example code, the letter "P" is used. This indicates that the tire is designed for a passenger car. However, it could also be an "LT" (for light truck), "ST" (for special trailer), or "T" (for temporary, usually seen on a donut spare).
  • Three-digit number. The three-digit number after the vehicle class is how wide the tire is. This is usually measured at the widest point of the tire from both edges, and is called the nominal section width. In the example above, this tire has a 215 mm nominal width.
  • Slash. The slash is nothing more than an indicator showing that there is a break in the code. Typically used to separate two different sections of code from each other for an easier time of reading and understanding.
  • Two or three digit number. Following the slash is usually a two or three digit number that is used to indicate the height of the sidewall. This height is typically represented in a ratio called an "aspect ratio" that is the height to the total width of the tire. For example, in this code that would be 65 percent (or 139.75 mm). If the number is higher than two hundred then it is assumed that it is the diameter of the entire tire in millimeters.
  • Letter. The letter that follows the two or three digit combination is purely optional used to indicate how the tire was constructed, but there are three common letters used. In the example provided you will see that there is an "R" which indicates that this tire is a radial tire. The other two commonly used letters are "B" (for belt) and "D" (for diagonal). If you don't see a letter it means that the tire is a cross ply tire.
  • Two-digit number. Next comes another two digits, which indicate the diameter (in inches) of the wheel that the tire is designed to fit. In the example provided here, the tire was designed to fit a 15-inch diameter wheel.
  • One or two digit and letter combo. The last three alphanumeric combination found in our example (and usually found on most tires) is indicative of the load and speed rating for the tire. Our example was rated at 95, which means that it can carry a maximum weight of 690 kilograms (or 1,500 pounds) per tire, and can go up to 130 miles per hour safely.

Author Bio

Lee Wyatt

Contributor of numerous Tips.Net articles, Lee Wyatt is quickly becoming a regular "Jack of all trades." He is currently an independent contractor specializing in writing and editing. Contact him today for all of your writing and editing needs! Click here to contact. ...


Driving on Wet Roads

Wet roads can present unique difficulties, even more so for the new driver. Here are some tips that can help when you are ...

Discover More

Designing Your Own Closets

A common dream for homeowners is to have their very own custom closets. While it would be wonderful to be able to hire ...

Discover More

Keeping Clothes Safe From Moths

Moths can be a major hassle, particularly for woolen clothes. While there are some traditional methods for keeping ...

Discover More
More Car Tips

When is it Time to Replace Your Tires?

Anyone who has ever owned a vehicle has asked themselves 'When is it time to replace my tires?' While you may think that ...

Discover More

Choosing Winter Tires

Choosing winter tires is not as simple as just going down to you local tire store and buying the ones that look good. ...

Discover More

Rotating Your Car Tires

Rotating your car tires is one of the many maintenance items that you can either pay good money for someone else to do, ...

Discover More

If you would like to add an image to your comment (not an avatar, but an image to help in making the point of your comment), include the characters [{fig}] (all 7 characters, in the sequence shown) in your comment text. You’ll be prompted to upload your image when you submit the comment. Maximum image size is 6Mpixels. Images larger than 600px wide or 1000px tall will be reduced. Up to three images may be included in a comment. All images are subject to review. Commenting privileges may be curtailed if inappropriate images are posted.

What is six less than 9?

There are currently no comments for this tip. (Be the first to leave your comment—just use the simple form above!)