How Do I Check A Tire's Speed Rating?

It's a very common question -- what is the speed rating on my tires? And of course, what does that mean? The practice of branding a speed rating on tires began in Germany, where some highways don't have speed limits, as a way to ensure the speed capability of the tires were matched with the top speed capability of the vehicle they’re mounted on.

Using the P195/60R15 87S tire in the image below as our example, the speed rating is denoted by the "S" at the very end.

Great, so what does an "S" speed rating mean? Each "letter" speed rating corresponds to a specific maximum speed. You can see from the table below, an "S" speed-rated tire has a fixed maximum speed of 112mph. It’s important to note speed ratings only apply to tires that have not been damaged, altered, or driven under-inflated or while overloaded.

The most common tire speed rating symbols, maximum speeds and typical applications are shown below:

When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of vehicles that have extremely high top-speed capabilities.

While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire's 168 mph, 270 km/h maximum speed.

When the Y-speed rating indicated in a service description is enclosed in parentheses, such as 285/35ZR19 (99Y), the top speed of the tire has been tested in excess of 186 mph, 300 km/h indicated by the service description as shown below: