What Are All Those Things Written On My Tires?
There’s More Than Just A Brand Name
You might expect there to be a brand name on the side of your tires. When you discover that there’s a lot more, you may feel a bit confused. What does all that writing mean? You don’t have to sweat the details. Dynamic Automotive in Urbana, Maryland, is here to help you with that. For more than 25 years, we’ve been helping drivers decipher the codes and get on with the business of tire purchases and services.
Deciphering the Writing
We don’t want you to be overwhelmed by the writing on your tires. There’s a lot of useful information written on the sidewall. It’s abbreviated, but that’s necessary to fit everything onto the tire. Here are a few pointers to help you feel more confident in what you’re seeing. Most of what you’ll read on the tire provides industry standards and US Department of Transportation (DOT) facts. The first letter, for instance, gives you the class. US tires are marked with a P to indicate passenger car and an LT for a light truck. (European metric tires omit this information.) After those first letters, you’ll see a 3-digit number which indicates the width of the tread from one sidewall to the other. It’s given in millimeters (mm). A tire showing 225, for example, has a tread width of 225 mm between sidewalls. The next numbers followed by an R express the tire’s aspect ratio. This is the relationship between the tread and the sidewall height. It’s expressed as a percentage. If a tire is marked as 45 R, the height of the sidewall is equal to 45% of the tread width. Next, you’ll notice a letter from A to Z. This provides the speed rating which is the highest speed at which the tire can be driven if that tire is in prime condition. Consult a reference chart to find each letter’s range. AZ has the highest speed rating. (Tires rated with a Z also have W and Y ratings after the load index. These give a more realistic maximum safe operational speed.) If you see another R, it indicates that the tire is a radial which has layers of cords.
The next 2-digit number is the diameter. For example, 17 tells you that the tire has a 17-inch diameter. The following multi-digit number shows the load index. This provides information about how much the tire can carry. As stated, the last letter gives the operation speed rating. On other areas of the sidewall, you’ll find the mandatory DOT markings, which include the manufacturer’s plant location, tire size, maybe tread pattern, and manufacture date. The Uniform Tire Quality Grading (UTQG) mark shows durability and weather-related operational information. The PSI shows the maximum amount of inflation. How can you make understanding the tire facts even easier? Visit Dynamic Automotive in Urbana, MD, your local tire experts.