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Tire Speed Rating: A Simple Explanation

6/7/2021
Tire Speed Rating: A Simple Explanation

From June 28 through July 4, 2021, the U.S. Tire Manufacturers Association (USTMA) announced it will launch its yearly consumer tire safety awareness campaign, National Tire Safety Week. This year's theme is "Do Your Part, Know Your Roll." National Tire Safety Week aims to educate drivers on the easy and important measures they should be taking to ensure their tires are always safe to drive. Other companies that are part of the USTMA, including Bridgestone, Cooper, Goodyear, Michelin, Toyo, and Yokohama, are also planning consumer-focused initiatives. Read on to learn what a tire's speed rating system is and how it works!

At Rent A Wheel we always drive the speed limit and certainly do not condone any reckless driving behavior like speeding. But have you ever wondered just how fast your car could go if you really pushed it?  There are many factors involved with this question: How heavy is your car? What kind of engine do you have? Do you have those sick flame decals on the side? But something you may not always think about is just how fast your tires are able to go. 

Tires can only handle so much speed

How fast your car can go depends on how fast your tires can handle going. Let’s say we’re in Germany for this discussion on the Autobahn in a section with no speed limit (did you know there actually are sections of the Autobahn that do have speed limits? Fun fact of the day.)

You car itself can speed up to 120 miles per hour before everything starts getting a little too fast to handle. You’ve got your hands at ten and two because you’re a safe driver and everything feels in control. But suddenly your tire literally explodes and you’re in a world of trouble- what happened? 

Well it turns out your tires were only rated to go 112 miles per hour and couldn’t handle the intense speeds you were doing on the unlimited section of the German Autobahn. They straight up expand due to high heat and pop because they weren’t rated for that intensity. 

What is the Tire Speed Rating System?

To find out just how fast your tires are rated to go before ripping across a German highway we just have to look at the tire and find the letter that will tell us where it lands on the Speed Rating Chart. This chart has been designed to simply tells us the maximum speed the tire can handle before overheating. There are a lot of letters on the chart and it can be a little confusing to look at in its entirety at first. Initially it looks like it might be in alphabetical order, but then you realize there’s eight different “A” ratings, there is no “O” or “Z” rating, “H” is all the way towards the end. 

But for most commercial vehicles like ours we can narrow this scope down to about five or ten letters to look for. 

Q: 99 mph.

R: 106 mph.

S: 112 mph.

T: 118 mph.

U: 124 mph.

H: 130 mph.

V: 149 mph.

W: 168 mph.

Y: 186 mph*

*You probably aren’t going to have a speed rating of 186 miles per hour but we thought we would include those numbers just to see how high they go.

I see what I’m looking for, but where is it? 

At Rent A Wheel we make finding the Tire Speed Rating letter as simple as possible. Let’s say you’re looking for a new set of tires after your Autobahn incident. You’re browsing our wide selection and you land a set of sweet Dunlop SP Sport 7000 A/S’s- all season tires built for performance that will get you going wherever, whenever, for as low as $21 a month. 

Take note of the drop down option that’s titled, “Size.” You’ll see a lot of numbers and letters, let’s use these Dunlop tires as our example tire and break these down. 

All those numbers and letters on the Dunlop’s look like this: 

P215/60R16 94H

Width: That first number, 215 is the width measurement of the tire from sidewall to sidewall, in millimeters. The tire might bulge out slightly towards the top, but this number is important because you need your tires to fit onto your rims, obviously. So you want to make sure the width of the tire and the width of your rims match. 

Aspect Ratio: No, we aren’t talking about film perspectives you movie buff- but it actually sort of is the same idea. The aspect ratio is the relative amount of height the tire has to its width. So the number 60 signifies that the height of the tire is equal to 60% of its width. (That’s the height from where the sidewall begins to the tread, not from where it touches the ground to the highest point, mind you.)

Construction: This is one you’re going to mostly see the same of no matter what tire you’re looking at. It just means that the layers built inside of the tire is radial, as shown by the letter R.

Wheel Diameter: Maybe you remember this one from geometry. The diameter is the measurement from one point of the tire to the other, straight across. The 16 is saying that this tire is built for a rim 16 inches in diameter. Not to be confused with the width. 

Load Index: We get to the load index at the end of this sequence. Well almost the end. As we’ve discussed, the load index number dictates what amount of weight this tire is rated for. In this case, the Dunlop tires have a Load Index Number of 94, meaning that it can support 1,477 pounds per tire. Multiply that by four and you’ve got a set of wheels that can hold 5,908 pounds. Not too shabby!

Speed Rating: Finally we get to the last letter! This is the speed rating identifier. This letter relates to the Tire Speed Rating Chart. As we’ve mentioned each letter tells you how fast the tire is recommended to go at maximum speed. So on our shiny new Dunlop SP Sport 7000 A/S’s, they have a Speed Rating number of H, which on the chart tells us we can safely go 130 miles per hour. According to the tires, not speed laws, which Rent A Wheel always obeys. But you would be all clear to go back and do 120 on the Autobahn with these. 

If you didn’t pop a tire on the Autobahn and want to check your existing tires.

So you’re looking at the tires you currently have and actually want to know how fast you can go before they explode on the road, great idea. Where would you look?

You could look up what tires you currently have online, or more than likely you can just look straight on the tire. It should have all of this information stamped right on to the rubber sidewalls, a long with a ton of other information. 

You’ll see the brand name, the tire name, temperature information, tread ware rating… a bunch of information. And it is all important. But as you keep looking around the tire you should see some familiar numbers and letters start to pop up- All of the information we discussed above should be there and you’ll see the same “P215/60R16 94H.” You know you’re looking for the letter at the end of that string, it might not be an H if you don’t have performance tires but that’s the speed rating letter you’re looking for! 

Important things to remember.

We won’t harp on this anymore but just a reminder- your Tire Speed Rating is a reflection of how fast your tire can go, not should go. This is the maximum capability of the material your wheels are made of, and you should always obey traffic laws and street signs. 

Also, make sure to always pair tires of the same speed rating on the same axle at least. Generally speaking you should always get a full set of the same tire on all four wheels, which we make incredibly convenient on our online store. If for some reason you don’t and your front and rear axle have different speed ratings, always listen to whichever tires have the lower speed rating. 

If your front tires have a speed rating of “H” which is 130 miles per hour, but your rear tires have a speed rating of “T” which is 118 miles per hour, then your overall speed rating is only 118 miles per hour. Exceeding the Tire Speed Rating of any tire is a recipe for trouble as we learned on the Autobahn. 

Tire Speed Rating Pro.

So now you know what the Tire Speed Rating System is. You know where to look for it when you’re shopping for new tires and how to check the rating on your existing tires. You know what all the letters mean and have a reliable source to check all of them. 

At RentAWheel.com you’ll find we have a wide selection of tires, from all season high performance tires to tires that specialize in off roading, snow and mud. All of theses tires have different functions, and it’s very important to know exactly what you’re looking for and what you’re expecting your tires to handle.

We make all of this simple when you’re shopping, and now that you’re an expert in the Tire Speed Rating System you probably don’t even need help when shopping. But if you do we have an excellent chat system where we can assist you finding the perfect tires for your dream machine, all for a great price. 



 

Sources:

A Concise History of Germany's Autobahns - Automobile

https://www.safercar.gov/Vehicle-Shoppers/Tires-Rating/Passenger-Vehicles

https://www.nhtsa.gov/equipment/tires

https://www.ustires.org/