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Did you ever look closely at the outside of a tire and wondered what the number sequence on the sidewall means? Those numbers are not random, nor is their placement. The numbers on your tire’s sidewall impart valuable information that every driver should know.

Savvy tire shopping

A person looking at the tire's sidewall.
A person inspecting tires | Getty Images

When shopping for tires, there are several things to consider. Climate is one of those things. If you live and drive in sunny Florida, you can get along happily with a well-made set of all-season tires. If you live upstate New York, you may want to invest in snow tires for part-time use. There’s more to consider than just your local climate, though.

According to S&S Tire of Lexington, Kentucky, the first thing to consider is your vehicle manufacturer’s recommendation. You’ll also want to think about ride quality. A set of tires may look great, but if the tread makes a lot of road noise, your daily commute may be less than comfortable. Speed rating and tire type are other factors to consider before buying new tires.

All of this info can be found on the sidewall. Understand the sidewall code, and you can learn everything you need to know about every tire you see.

Break the tire code before you go tire shopping

Known as the tire code, the numbers, and letters molded into the sidewall of a tire tell you more than just the size. Required by the Department of Transportation (DOT) since 1971, the alphanumeric sequence on the side provides crucial data for each individual tire, including:

  • Load index
  • Maker of the tire
  • Physical features, including width and aspect ratio
  • Rim diameter
  • Speed rating
  • Vehicle classification
  • When and where the tire was manufactured

Goodyear Auto Service breaks down DOT tire code P215/65R15 95H explaining that the P at the start of the sequence indicates a tire for a passenger vehicle. The following three numbers refer to the width in millimeters from one sidewall to the other. In this case, the width is 215 mm.

The two numbers after the slash are the ratio of the height and width of the tire. In this case, the aspect ratio is 65, indicating the tire height measures 65 percent of its width.

The following letter, a capital R, means it’s a radial tire. The two digits after the R reveal the diameter of the wheel for which the tire is made. In this case, the tire is meant for a 15-inch wheel.

Goodyear did not explain the 95H at the end of the sequence. Underriner Automotive says that part of the code refers to the speed rating and load index of the tire.

Safe tires you can count on in any situation

Unless something goes wrong, most people don’t think twice about the tires on their cars. Those who look closely can glean valuable information just by a tire’s appearance.

If you know nothing about tires, your best bet might be to take your car to the dealership for a new set of rubber. You’ll get the right tires, but you could wind up paying a lot more than if you purchase after-market tires and have them installed. Be careful when shopping for your own tires, though. Understand the DOT sidewall codes before you go so you don’t get sweet-talked into buying the wrong tires.

Tires help you accelerate, navigate corners, and stop when necessary. In fact, tires are some of the most critical safety features on your vehicle. Know what you need and choose wisely when you understand the meaning of the letters and numbers on every tire sidewall.


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