TIRE SPEED RATING SAFETY
So, what is a tire speed rating, and why is it so important? Given in letters, your tire’s rating determines its maximum safe operating speed. In short, speed ratings directly impact how fast you can drive.
But the impact doesn’t stop there. Because your tire’s speed rating is determined by how the tire was constructed, tire speed ratings can also affect how your vehicle handles.
To maintain your vehicle's original performance and handling characteristics, be sure to equip it with tires that meet or exceed the original equipment (OE) tire's speed rating. One of the easiest ways to make sure your new tires have the appropriate speed rating? Letting Treadwell help you find the right tires for your ride!
If you equip your vehicle with tires of different speed ratings, the lowest tire rating determines your vehicle's safe top speed. However, you should always obey legal speed limits, regardless of your tire speed rating.
You can find your tire's speed rating by reading the size code on the tire’s sidewall. Typically following the load index, your tire rating is represented by a letter that directly corresponds to the tire’s max speed.
For the most part, a tire’s max speed increases in direct correlation with where its letter designation sits in the alphabet. For example, a tire with a W speed rating can operate at a higher speed than a tire with an L speed rating. However, not all ratings follow this rule. Read about unique speed rating exceptions after the tire speed rating chart below!
| Speed Rating | Maximum Speed |
|---|---|
| B | Up to 31 mph |
| C | Up to 37 mph |
| D | Up to 40 mph |
| E | Up to 43 mph |
| F | Up to 50 mph |
| G | Up to 56 mph |
| J | Up to 62 mph |
| K | Up to 68 mph |
| L | Up to 75 mph |
| M | Up to 81 mph |
| N | Up to 87 mph |
| P | Up to 93 mph |
| Q | Up to 100 mph |
| R | Up to 106 mph |
| S | Up to 112 mph |
| T | Up to 118 mph |
| U | Up to 124 mph |
| H | Up to 130 mph |
| V | Up to 149 mph |
| W | Up to 168 mph |
| Y | Up to 186 mph |
| Z | 149 mph and over |
UNIQUE SPEED RATINGS
While most tire speed ratings increase in max speed the further along the alphabet they are, there are a few notable exceptions to this rule. In this system, tires with a Z rating would be the fastest rated tires out there. At one time, Z-rated tires were thought to be the highest rated tires a vehicle would need.
But the development of faster vehicles brought us two new speed ratings: W and Y-rated tires, both of which are rated for higher speeds than the Z despite their earlier place in the alphabet. These speed ratings provide a more precise indicator of a high-performance tire’s speed over 149MPH.
Typically, the Z, W and Y ratings appear on summer tires or competition tires commonly found on sports cars, tuners, exotic cars and other vehicles built for thrilling UHP performance.
H is the only other speed rating that doesn't appear in alphabetical order. A holdover from the early European speed rating system, the tire experts of the time chose not to change the original rating indicated by H.
ORIGINS OF TIRE SPEED RATINGS
Tire speed ratings first originated in Europe in the 1960s as a way to make sure increasingly faster vehicles were equipped with tires that could safely handle the demands of higher power and faster speeds.
These early speed ratings set the foundation for the tire speed rating system still in use by the DOT and tire manufacturers today.
To determine the tire’s speed rating, a technician places a properly inflated tire in a drum that rotates the tire for 10-minute intervals at increasing speeds. The technician then verifies the tire’s speed rating by confirming the maximum speed the tire was able to go while retaining its structural integrity.
Because speed ratings are determined in controlled lab conditions, they don’t indicate a speed you can consistently maintain in real-world driving. They instead determine the tire’s capacity to reach and sustain a certain speed for a particular length of time.
If you have any questions or require any assistance, stop by any of our Discount Tire locations and we'll get you taken care of! Customers who buy and book online save time in-store!