What do the numbers and letters on tires mean?
2 Answers
The numbers and letters on tires represent: 1. The first number indicates the tire's section width, which is the width of the tire's contact surface with the road during normal driving, measured in millimeters; 2. The second number represents the tire's aspect ratio, and the letter R indicates that the tire is a radial tire; 3. The last number indicates the wheel diameter. A commonly referred to 17-inch tire actually means the wheel diameter is 17 inches. Generally, ordinary cars have wheel diameters between 15 to 18 inches, while luxury cars may have larger wheel sizes. Larger wheels offer better visual appeal and can provide the car with improved stability.
As a long-time driving enthusiast, I find that the numbers and letters on tires actually hold significant meaning. For example, 225 indicates the width is 225 millimeters—wider tires provide better grip in rainy conditions. The 65 is the aspect ratio, representing that the sidewall height is 65% of the width; a lower value means a flatter tire, which improves cornering stability. The R that follows stands for radial construction, a design used by almost all modern vehicles. The 15 is the rim size in inches, so when changing tires, you must match your wheel hubs. Another example is the load index, like 95, which corresponds to a carrying capacity of approximately 690 kilograms—overloading can easily lead to blowouts. The H is the speed rating, supporting a maximum of 210 km/h, which is sufficient for daily highway driving. Also, don’t forget the date code, such as 3923, indicating the tire was manufactured in the 39th week of 2023—older tires show noticeable performance degradation. Checking these indicators before selecting tires can enhance both driving safety and the overall experience.
