What do the numbers and letters on car tires represent?
2 Answers
The numbers and letters on car tires represent the following meanings: 1. Section width: The increased width of the tire and its contact area with the ground enhances grip and improves braking performance; 2. Aspect ratio: The ratio of the tire's section height to its section width; 3. Radial tire and rim diameter: Common tires are denoted by 'R', indicating a radial tire, where the internal cord fabric is arranged at a 90-degree angle to the tire's centerline, resembling the meridians on a globe; 4. Load index: A numerical value representing the maximum load capacity, indicating the maximum weight the tire can bear under normal inflation conditions; 5. Speed rating: The maximum speed at which the tire can carry a specified load under defined conditions.
I've been repairing cars for twenty years and am very familiar with these markings on tires. Take the common P215/65R15 95H as an example: P stands for passenger vehicle tires, 215 is the tread width in millimeters, 65 is the aspect ratio indicating that the height is 65% of the width, R represents the radial structure which is the standard design for modern tires, and 15 is the rim diameter in inches. 95 is the load index, meaning each tire can carry 690 kilograms, and H is the speed rating with a maximum of 210 kilometers per hour. The tire sidewall also has a DOT code like 3522, where the last four digits show the production week 35 and year 22, meaning it was manufactured in the 35th week of 2022. Tires older than six years are prone to cracking and should be replaced promptly. Don't forget to check the MAX PRESS value for tire pressure, and it's generally recommended to inflate them regularly to maintain safety.
