How to Read the Sidewall of a Tire
Your tire has very useful information molded into the sidewall. It shows the name of the tire, its size, whether it is tubeless or tube type, the maximum load and maximum inflation, the important safety warning and much other information.
Shown below is the sidewall of a popular "P-metric," speed-rated auto tire. "P" stands for passenger; "215" represents the width of the tire in millimeters; "65" is the ratio of height to width; "R" means radial; "15" is the nominal rim diameter code; and "95H" is the optional service description that consists of the load index (95) and the speed symbol (H). Some older speed-rated tires may include the speed symbol immediately before the "R" instead of showing a service description.
Typical Passenger Tire
A "B" in place of the "R" means the tire is belted bias construction. A "D" in place of the "R" means diagonal bias construction. "M+S" with the mountain/snowflake symbol is the designation that the tire meets the RMA (Rubber Manufacturers Association) definitions for use in severe snow conditions.
The maximum load is shown in kg (kilograms) and in lbs (pounds), and maximum pressure in kPa (kilopascals) and in psi (pounds per square inch).
The letters "DOT" certify compliance with all applicable safety standards established by the Department of Transportation (DOT).
Adjacent to this is a tire identification or serial number. This serial number is a code with up to 12 digits that are a combination of numbers and letters. The last characters are numbers identifying the week and year of manufacture. (Example: "1501" means fifteenth week of the year 2001.)
The sidewall also shows the type of cord and number of plies in the sidewall and under the tread.
The DOT requires tire manufacturers to grade passenger car tires based on three performance factors: treadwear, traction and temperature resistance.
Typical Light Truck Tire
Source: Rubber Manufacturers Association