Tire speed ratings are set by the tire manufacturers and are an indication of the tire’s maximum speed capability in ideal conditions. The tire load index rating communicates how many pounds a tire can safely carry. Put together, they make up the service description.
Knowing this service description information is highly recommended whenever you’re replacing Original Equipment (OE or factory) tires. Even if you don’t plan on pushing limits in speed or load categories, matching or improving the speed rating and load index of your factory tires will help keep your vehicle’s performance characteristics consistent.
Most tires are constructed to reflect the more common, practical speeds of everyday commuters with a quite significant safety buffer on the top end. Tire speed rating is communicated with the final letter in the tire service description, and each letter translates to a specific top speed in miles per hour.
Both speed rating and load index are part of a group of (three) digits at the tail end of the tire size information. Together these figures make up the tire’s service description.
If your vehicle is still equipped with its factory tires, you can refer to the driver’s side doorjamb placard, which includes tire information.
In the doorjamb image above (belonging to an Audi A3), the car’s tire information is: 225/45R17 94H. In this example, 94H is the service description, with the 94 indicating load index, and the H indicating speed rating.
You can also find this information printed on the sidewall of all tires.
Speed rating is established under controlled testing where – once again, under optimal conditions – the tire is verified as capable of safely running at (up to) the indicated miles per hour. Heavily worn, damaged, punctured, or repaired tires would all be considered sub-optimal, and no longer capable of safely accomplishing their max speed rating.
|Speed Rating||Miles/Hour||KM/Hour||Typical Application(s)|
|Q||99||160||Select winter tires|
|R||106||170||Passenger and light truck tires|
|S||112||180||Passenger and light truck tires|
|T||118||190||Passenger and light truck tires|
|H||130||210||Passenger sedans, coupes, SUV and CUV?s tires|
|V||149||240||Performance sedans, coupes, and sports cars tires|
|W||168||270||Performance sedans, coupes, SUV and CUV?s tires|
|Y||186||300||Exotic sports cars tires|
|Z||149+||240+||High-Performance vehicle tires|
Going back to our Audi, the H speed rating is equal to 130 miles per hour, meaning that under optimal conditions, the tire can perform at speeds up to 130 mph. The speed rating doesn’t imply the vehicle can drive that speed, but the tires are capable of supporting the car at that speed.
Most boat and utility trailer tires have this speed rating which is a maximum of 75mph
An M indicates the tire has been approved for speeds up to 87 mph (140 km/h) and an N is approved for speeds up to 81 mph (130 km/h) under optimal conditions. You’ll find M and N ratings on tires for temporary use like spare tires.
A P indicates the tire has been approved for speeds up to 93 mph (150 km/h) under optimal conditions.
P tires are uncommon these days. Even tires with specialty function and performance such as winter tires and off-road tires typically achieve at least a Q speed rating.
Q tires are approved for speeds up to 99 mph (160 km/h) under optimal conditions. Tires toward the low end of the speed rating range often prioritize a particular function or unique performance over maximum speed rating. Some studdable and studless winter tires, for example, are Q speed rated.
Speed rating R allows for speeds up to 106 mph (170 km/h) under optimal conditions. Like Q, R tires generally prioritize a particular function or unique performance over maximum speed capability. R speed tires are rare but can be found on some heavy-duty light truck (LT) tires, as well as studdable and studless winter tires.
An S speed rating indicates the tire has been approved for speeds up to 112 mph (180 km/h) under optimal conditions. Everyday passenger vehicle tires can be S speed rated, but S tires often prioritize specific performance or function. Many all-terrain LT tires are becoming available in an S rating as that’s the OE spec for many of these vehicles like the Ford Raptor.
A T rating indicates the tire is approved for speeds up to 118 mph (190 km/h) under optimal conditions. T ratings are most associated with standard touring tires, and everyday passenger vehicles like family sedans and minivans.
An H speed rating indicates the tire is approved for speeds up to 130 mph (210 km/h) under optimal conditions. An H speed rating is at the low end, or at the start of the performance tire speed ratings. H speed rated tires are ideal for sport and luxury coupes and sedans, but not typically considered full-fledged performance vehicles. H speed ratings are common in the grand touring all-season tire category.
A W means the tire is approved for speeds up to 168 mph (270 km/h) under optimal conditions. W speed rated tires land firmly at the performance end of the speed rating spectrum. Ws are suitable for performance coupes and sedans, and even street driven exotic sports cars.
W speed rated tires generally offer plenty of performance for the street, including “spirited” (but responsible) drivers. At the same time, W tires don’t necessarily sacrifice everyday driving factors like comfort (ride quality, road noise), and treadlife warranty.
A V rating indicates the tire is approved for speeds up to 149 mph (240 km/h) under optimal conditions.
H and V tires often go hand in hand. While the V rating technically allows for a higher maximum speed, practically speaking, this a distinction without much of a difference (in light of U.S. speed limits). Like H tires, Vs can deliver a taste of the performance attributes associated with high speed rated and high-performance tires (W, Y, and Z).
Y rated tires have been tested at speeds up to, and in excess of, 186 mph (300 km/h) under optimal conditions. If Y speed rating is indicated without parentheses (as normal), this means the tire is rated up to 186 mph. If the Y speed rating is indicated inside of parentheses, this means that particular tire size and specification has been tested at speeds in excess of 186 mph. A Y speed rating denotes maximum tire performance.
A Z rating indicates the tire has been approved for speeds of 149+ mph (240+ km/h) under optimal conditions. This rating is associated with maximum tire performance and is a match for performance coupes and sedans, sports cars, and supercars. While speed rating is typically adjacent to the load index, and outside of (after) the tire size expression, the Z speed rating can be found within the structure of the tire size:
To understand the speed restriction of a Z speed rated tire, refer to the additional speed rating adjacent to the load index. In the case of a Z tire, the speed rating will either be W, Y, or (Y).
The one outlier here is the Z rating, which pertains to only high-performance tires. You won’t find Z indicated within the service description as usual. Instead, the Z is integrated as part of the tire size information on high-performance tires.
Decades ago, the Z speed rating was established as a catchall for any high-performance tires built to exceed speeds of 149 mph. Greater specificity was not considered necessary.
But with the introduction of an increasing number of performance vehicles capable of approaching and even exceeding the 200 mph mark, speed ratings were expanded to give greater specificity to the actual top speed limitation.
Now that we’ve covered top speed limitation, let’s dive into how much weight your tires can carry by reading the tire’s load index.
The tire load index rating communicates how many pounds a tire can safely carry.
Going back to the Audi example, the car’s service information is: 225/45R17 94H. 94 indicates the load index. Referring to the tire load rating index chart below, the number 94 translates to a load-carrying capacity of 1477 pounds (per tire).
While you’re probably unlikely to approach the top speed rating of your tires, pushing load index ratings is more common, especially when it comes to hauling and towing with trucks and SUVs. Use the chart below to understand the weight limitations of your vehicle’s tires. Additional attention should be paid to the vehicle’s hauling and towing limits, which are set by the manufacturer and involve tire capacity, as well as drivetrain and other considerations. Check your vehicle owner’s manual for details.
Note: You should never replace your tires with a lesser speed and load rating than the original equipment tires.
You can replace a tire/your tires with a high-speed rating and load rating.
|Load Index||Pounds (lbs)||Kilograms (kg)|
|Load Index||Pounds (lbs)||Kilograms (kg)|
|Load Index||Pounds (lbs)||Kilograms (kg)|
|Load Index||Pounds (lbs)||Kilograms (kg)||Load Index||Pounds (lbs)||Kilograms (kg)||Load Index||Pounds (lbs)||Kilograms (kg)|
On the search for a new set of tires? On TireBuyer we’ve made it easy to find replacement tires that meet or exceed the speed rating and load index of your factory tires.
To shop for tires, share the year, make, and model of your vehicle. When you start your search, every tire that’s offered will match not only your factory tire size(s), but also the speed rating and load index of your factory tires.
Have additional questions or concerns about speed rating and/or load index? Give our tire experts a call at 866-961-8668.