Understanding the information on your tire's sidewall is essential for maintaining your vehicle's performance and safety. The sidewall of a tire contains a wealth of information, from the tire's dimensions and type to its capacity and speed rating. This guide will help you decode this information, ensuring you make informed decisions about your tires.
Tire Size
One of the most prominent pieces of information on a tire's sidewall is its size. It's usually represented in a sequence like this: P215/65R15.
- P: This letter indicates the tire's type. "P" stands for passenger vehicle tire. Other types include "LT" for light truck, "T" for temporary (spare), and no letter for European metric tires.
- 215: This number represents the tire's width in millimeters from sidewall to sidewall.
- 65: This is the aspect ratio, a percentage that shows the height of the tire's sidewall compared to its width. In this example, the sidewall height is 65% of the tire's width.
- R: This letter indicates the construction type of the tire. "R" stands for radial, which is the most common type of tire construction. Other types include "B" for bias belt and "D" for diagonal.
- 15: This number indicates the diameter of the wheel in inches that the tire is designed to fit.
Load Index and Speed Rating
Following the tire size, you might see a number and a letter, like 89H.
- 89: This is the load index, which tells you how much weight the tire can support when properly inflated. The higher the number, the more weight the tire can carry. You can refer to a load index chart to find the exact weight.
- H: This letter is the speed rating, indicating the maximum speed at which the tire can carry a load corresponding to its load index. "H" means the tire can go up to 130 mph. Speed ratings range from A (the lowest) to Y (the highest).
Other Sidewall Markings
- DOT: This signifies that the tire complies with all applicable safety standards established by the U.S. Department of Transportation. Following "DOT," the code provides information about the tire's manufacturer and place of production.
- Treadwear, Traction, and Temperature Grades: These ratings provide information about the tire's expected wear, traction performance, and resistance to heat. Treadwear is a comparative rating based on the wear rate of the tire when tested under controlled conditions.
- Maximum Inflation Pressure: This number indicates the maximum air pressure the tire can hold, not necessarily the recommended pressure for your vehicle. Always follow your vehicle manufacturer's recommended tire pressure.
- Maximum Load: Similar to the load index, this number indicates the maximum weight the tire can support.
Understanding Tire Sidewall Abbreviations
- M+S or M/S: Stands for mud and snow, indicating that the tire meets the Rubber Manufacturers Association standards for use in mud and light snow.
- All-Season: Tires marked with "All-Season" or "A/S" are designed to provide good performance in a variety of conditions, including wet roads and light winter driving.
- Tubeless: Indicates that the tire does not require an inner tube.
By understanding the information on your tire's sidewall, you can ensure that you're selecting the right tires for your vehicle, driving conditions, and safety requirements. Always consult with a tire professional if you're unsure about any specifications or need advice on the best tires for your needs.