TIRE SPEED RATING
A tire’s speed rating, also call its speed index, tells you the maximum speed a tire can safely maintain over time while carrying its maximum load (which is specified in the tire load index). It is marked using a letter from A to Z, which you can then use to look up the maximum speed in miles per hour or kilometers per hour.
The rating system was developed as a standardized way to communicate how different tires ability to perform at high speeds in a test environment. With the exception of the letter H and sometimes Z, the closer the speed rating is to the end of the alphabet, the better the tire will perform at high speeds.
How to find your tire’s speed rating
To find the speed rating your vehicle’s manufacturer recommends for your tires, look in your owner’s manual.
The actual speed rating of the tires currently fitted on your vehicle are molded onto the sidewall of your tire at the very end of your tire’s size code, following the load index.
For example, in a tire size code of P225/60R16 97V, the speed rating is V. You can use the chart below to convert these ratings into the actual maximum speed your tire is rated for.
Tire speed rating chart
Using the chart, we can see the tire is rated to withstand sustained speeds of up to 149 miles per hour.
It is important to be aware that this rating is based on a test environment with tires that have not been subject to any damage.
|Speed Symbol||Maximum Speed||Vehicle Type|
|L||75 mph||Off-Road & Light Truck Tires|
|M||81 mph||Temporary Spare Tires|
|O||99 mph||Studless & Studdable Winter Tires|
|R||106 mph||H. D. Light Truck Tires|
|S||112 mph||Family Sedans & Vans|
|T||118 mph||Family Sedans & Vans|
|H||130 mph||Sport Sedans & Coupes|
|V||149 mph||Sport Sedans, Coupes & Sports Cars|
|W||168 mph||Sport Sedans, Coupes & Sports Cars|
|Y||186 mph||Sport Sedans, Coupes & Sports Cars|
|Z||149 mph+||Sports Cars, Exotic Cars|
Why is speed rating so important?
The speed rating essentially reflects the ability of a tire to withstand or dissipate heat at high speeds. Running a tire at speeds higher than its rating can shorten the tire’s life and potentially lead to a tire damage which could result in an accident, so it is important to follow the manufacturer’s speed rating recommendations when you are choosing tires.
The speed rating should never be taken as the safe maximum speed of your vehicle, or as a recommendation that you should travel faster than the legal speed limit. The actual safe driving speed depends on many other factors, such as laws, weather and road conditions, and your car’s mechanical capabilities and condition. If a tire is old, worn down, underinflated or overloaded, the speed rating is no longer relevant.
Difference between speed rating and load index
The load index and speed index show up together as the last part of the tire size code.
The load index is a two or three digit number, while the speed index is a single letter at the very end of the entire size code. In the example above, the load index is 97, while the speed index is V.
Light truck tire speed rating
Light truck tires use the same single-letter speed rating system as other tires.
However, light trucks are not designed to travel as fast as passenger cars, so they often have lower speed ratings (often ranging between N and H).
How to read your tire?
In addition to the speed index, your tire’s sidewall contains a lot of other key information.
You can find a more in-depth description about the tire code and other markings with details on size, safety, and performance by clicking on the hyperlink.
Find your tires
Using the information on tire speed ratings in this article, you can search Pirelli’s catalog to find tires for your size and speed rating.