Speed rating on tires: What you need to know

by | Sep 22, 2022

speed rating on tires what you need to know

If nothing on your tire’s sidewall makes any sense to you, don’t worry, you aren’t alone. What may seem to be a collection of random numbers and letters actually signify the properties of your tires, from its size to its load index. But one of the most important factors is represented by a single letter and it’s your tire’s speed rating. As its name suggests, the speed rating is the maximum speed a tire is safely rated for, but it’s certainly not helpful when it’s designated by a letter and not a number.

To help make sense of all this, we’ve created a table of tire speed ratings and their maximum speeds. Naturally, many of these aren’t commonly used these days.

Speed ratings / maximum speed

Speed RatingMaximum Speed (mph)Maximum Speed (km/h)
A13 mph5 km/h
A26 mph10 km/h
A39 mph15 km/h
A412 mph20 km/h
A516 mph25 km/h
A619 mph30 km/h
A825 mph40 km/h
B31 mph50 km/h
C37 mph60 km/h
D40 mph65 km/h
E43 mph70 km/h
F50 mph80 km/h
G56 mph90 km/h
J62 mph100 km/h
K68 mph110 km/h
L75 mph120 km/h
M81 mph130 km/h
N87 mph140 km/h
P94 mph150 km/h
Q99 mph160 km/h
R106 mph170 km/h
S112 mph180 km/h
T118 mph190 km/h
U124 mph200 km/h
H130 mph210 km/h
V149 mph240 km/h
Z149+ mph240+ km/h
W168 mph270 km/h
Y186 mph300 km/h
(Y)186+ mph300+ km/h

What’s up with H and Z speed ratings?

As you might be able to tell, the original idea for speed ratings were to do them alphabetically. The “H” rating however stands out, slotted between “U” and “V” at 130 mph or 210 km/h. It’s widely believed that “H” symbolized “high performance” at one time, which explains why it breaks up the alphabetical naming convention.

As for when the “Z” rating was introduced, the letter was used to represent the highest tire speed rating that would ever be needed (or so they thought), which was 149+ mph or 240+ km/h. As for how above 149 mph Z-rated tires would be, it was never identified. Not surprisingly, the industry eventually realized it would need additional speed ratings as modern luxury and exotics achieved higher top speeds. This is when “W” and “Y” speed ratings were introduced.

speed rating on tires what you need to know 02
Photo credit: Smile Fight / Shutterstock.com

Can I mix tires with different speed ratings?

We do not recommend mixing tires with different speed ratings. If you absolutely need to mix tires, put the lower speed-rated tires in the front. It doesn’t matter if your car is front- or rear-wheel drive, having the lower speed-rated tires in the front will help prevent potential oversteer. Obviously, you should abide by the limit of the lower speed-rated tires when driving.

Where do I find my tire’s speed rating?

Most modern tires will have the speed rating as the final letter in the tire size’s code. But if your vehicle is riding on older rubber, you may have to look at your owner’s manual, driver’s side doorjamb, gas door, or glove box for your factory speed ratings. If we take the above image as an example, the tire size’s code is “225/45R19 92W”. That would mean the tire’s speed rating is W, or capable of going 168 mph or 270 km/h.

Speed rating ≠ top speed

Don’t think your tire’s speed rating is your vehicle’s actual speed capacity. Speed ratings are based on a new tire’s performance in lab testing conditions, not your typical roadways. There are a few factors that affect your tire’s actual safe maximum speed: tire inflation, tire condition, cargo load, road surfaces, and even weather. If your tire is underinflated or your vehicle is carrying a heavy load, the maximum safe speed is compromised. In addition, if your tire has been repaired — due to a puncture, for example — its speed rating is likely reduced.

What are the most common tire speed ratings?

On most family sedans and vans, you’ll typically find S- and T-rated tires. Sport sedans and coupes will typically have H-rated tires, while some sports cars will have V-rated tires. V-, W-, and Y-rated tires are most often found on high-performance vehicles and sports cars, along with some electric vehicles. You’ll find that most winter tires will have Q, S, or T speed ratings. On light trucks, you’ll typically find N, P, Q, and R speed ratings.

Are tires with higher speed ratings better?

For the most part, tires with higher speed ratings offer better performance in terms of handling and responsiveness. Those tires typically use softer rubber compounds and have stiffer construction, resulting in overall better steering response, cornering, and even stopping power. There are sacrifices to be made however, since those tires won’t ride as comfortably and generally have a lower treadwear rating. Also, they won’t perform as well in icy or cold conditions.

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