Tires are circular, pneumatically inflated structures that transfer load from an axle to a wheel. They are made up of a variety of materials, including natural rubber, petroleum, polyester, and nylon. Depending on the manufacturer, tires can be designed for different purposes.
The components of a tire include the tread, bead, carcass, and sidewall. These structures provide flexibility, cushioning, traction, and resistance to damage. Several factors affect the design of a tire, such as the type of driving the owner wants to do, the road conditions, and the vehicle.
Typically, a tire has a speed rating, which indicates the maximum speed that the tire can handle. This number is typically printed on the sidewall. Some tires also have a run flat or temporary spare digit, which means that the tire can be used to maintain a steady tread for a specified amount of time.
Aside from the size, the sidewall also contains other information. For example, “LT” denotes a light truck tire, which can be purchased in larger sizes. In addition, the sidewall often includes a load index, which determines how much weight the tire can carry.
Other data is found on the sidewall, such as the year of manufacture. An all-terrain tire will have a more aggressive tread pattern than a passenger car tire. Similarly, a special trailer tire will have the word “ST” or “ST-W” on the sidewall.
Aside from the speed and load ratings, a tire will have a DOT code. This alphanumeric code is used by the Department of Transportation (DOT) to track the production of tires. Specifically, the first two characters are the factory where the tire was manufactured, and the last four characters are the date of manufacturing.