The alphanumeric code embossed on a tire sidewall provides critical information about its size, construction, and performance capabilities. A typical sequence, such as P215/65R15 95H, breaks down into several distinct components. The initial letter indicates the tire type (P for passenger vehicle, LT for light truck). The subsequent three-digit number represents the tire’s section width in millimeters. The two-digit number following the slash denotes the aspect ratio, calculated as the sidewall height as a percentage of the section width. The letter ‘R’ signifies radial construction, and the subsequent two-digit number specifies the wheel diameter in inches. Finally, the numbers and letters at the end represent the load index and speed rating, respectively. The load index indicates the maximum weight the tire can carry at the speed designated by the speed rating.
Understanding these markings is essential for selecting appropriate replacement tires and ensuring vehicle safety. Correctly interpreting the load index and speed rating guarantees that the tires are capable of handling the vehicle’s weight and achieving its maximum speed. Moreover, adhering to the original equipment manufacturer’s (OEM) recommendations regarding tire size maintains accurate speedometer readings, prevents interference with vehicle components, and optimizes handling characteristics. Historically, these standardized markings evolved to provide a common language across tire manufacturers, allowing consumers to make informed decisions.
