The numbers and letters on that sidewall represent everything from the type and width of the tire to the aspect ratio, construction type, diameter, load index and. Whether you're changing your tires for a different look or for additional performance, a good starting point for looking for that new tread is the sidewall of one of your current tires. The numbers and letters on that sidewall represent everything from the type and width of the tire to the aspect ratio, construction type, diameter, load index and speed index. Here's how to read the sidewall of your tires.
You will then find a single letter, either a “D”, a “B” or an “R”, which indicates the type of construction of the tire. What do the numbers and letters on the side of the tire mean? These numbers can be intimidating at first glance, but we've prepared a simple guide to help you learn what these numbers and symbols mean and how you can use them to care for new tires or even to buy them. These numbers and letters will help you know the tire size, load index, speed index, Department of Transportation (DOT) serial number and more. Have you ever wondered what the designations stamped on the sidewall of the tire actually mean? We would like to break it down for you. Other types of tires that belong to the metric size type are temporary spare parts, which begin with the letter “T”.
If you see a size that starts with the letter “ST”, it means “special trailer” and can only be used on a trailer. From time to time, you may also see RF, which indicates a flat tire, or ZR, which indicates a tire with a speed rating greater than V. For example, a tire rated 150 would wear out one and a half times more on the government circuit than a tire rated 100. Tires that meet the RMA definition for passenger and light truck tires used in heavy snow conditions are marked on at least one sidewall with the letters M and S (as indicated above), in addition to the symbol of a mountain with a snowflake. Now that you know the meaning of your tire numbers, you can use them to understand their limitations.
Because the load ratings of a given tire size may vary, it's important to ensure that the tire you're considering meets or exceeds the vehicle manufacturer's specific requirements. They can be used to make comparisons within a tire manufacturer's product line, but due to variations in testing procedures, they should not be used to compare tires from one company to those made by another company. The tire code appears on the sidewall of the tire and will usually be the largest sequence of numbers and letters. The first number is the load index if the tire is used in a single application, the second number is the load index if the tire is used in a dual application.
This is because the maximum cold tire inflation pressure indicated on the sidewall only indicates the highest pressure allowed for that tire. The Uniform Tire Quality Rating System (UTQG) is a system developed by the Department of Transportation that helps consumers compare tires based on tire wear, traction and temperature. Since there can be large differences in tire handling and traction within a given speed category, speed ratings alone should not be used to determine tire choice. The speed rating is the last letter of the tire code and indicates the maximum speed a tire is designed for.
Follow the tire inflation pressure recommendations listed on the vehicle's tire plate, certification label, or owner's manual. There are other codes on some tires that give you additional information, some of which are specific to light truck tire applications. When the snowflake from the three mountain peaks (shown below) also appears on the list, this indicates that the tire is classified as a winter tire by I. The Tire and Tire Association governs a standard set of interchangeability guidelines for all tire manufacturers in the United States.
