What do the numbers and letters on tires mean?
2 Answers
The numbers and letters on tires mean: 1. Section width: A wider tire increases the contact area with the ground, enhancing grip and directly improving braking performance; 2. Aspect ratio: This is the ratio of the tire's section height to its section width; 3. Radial tire and rim diameter: Common tires are marked with 'R', indicating radial tires, also known as 'steel-belted tires'. Radial tires have internal ply cords arranged at a 90-degree angle to the tire's centerline, resembling meridians on a globe; 4. Load index: This is a number corresponding to the maximum load capacity, indicating the maximum weight the tire can bear under normal inflation; 5. Speed rating: This indicates the maximum speed at which the tire can carry a specified load under defined conditions.
That string of numbers and letters on the tire is no simple matter. I remember once when changing tires, the mechanic explained to me that a combination like P215/65R15 95H means: The P at the beginning stands for Passenger tire, specifically designed for regular family cars; 215 indicates the tread width is 215 millimeters—the larger the number, the wider and more stable the tire; 65 is the aspect ratio, meaning the height is 65% of the width, with a smaller number indicating a thinner tire for better handling; R stands for Radial construction, the modern mainstream type known for its durability and pressure resistance; 15 is the wheel diameter in inches, which must not be mistaken when changing tires; 95 is the load index, roughly corresponding to a load capacity of 680 kilograms; H is the speed rating, capable of speeds over 210 kilometers per hour. Choosing the wrong tire affects driving safety, especially increasing the risk of skidding or blowouts at high speeds. Every time I buy a car, I carefully check to ensure the tires match the manufacturer’s recommendations and also look at the DOT code on the tire sidewall to check the production date and avoid aging issues.
