Home / Tire Size and Speed Rating – What Do They Mean | Tire Ratings

Tire Size and Speed Rating – What Do They Mean | Tire Ratings

The tires of an automobile generally do not get as much care and attention as they actually deserve, Tires are easily among the most important external parts that make your cars complete, and have a huge impact on the safety and comfort of the drive that you experience. Thus, it is extremely essential that you get some knowledge about your car tires. This article discusses a very important piece of information about car tires, i.e., tire ratings. These are the markings and labels that you can find on your tires, and decode to extract valuable information as regards the characteristics of those tires.

Tire Ratings – What Do They Mean

tire ratings
Tire Ratings

Your tire’s rating might not make any sense to you in case you do not know how to interpret the combinations of alphabets and numerals. For instance, consider a rating such as LT275/75/R15. The initial part of it, i.e. LT, actually indicated that the tire with this rating is meant for use with a light truck. It could very well have been a P there, and it would have meant that the tires are supposed to be used with passenger vehicles. The next part of the rating, the set of numeral 275 in this case, indicates the width in millimetres of the tire. Before going into deeper details for this, it would be pertinent to mention that the tire width is a really important parameter that determines quite a few other variables such as the fuel efficiency of the tires. It is important to note that the reading given in the ratings can be easily translated into inches by using a dividing factor of 25.4 with the millimetre reading. So, the tire rated LT275/75/R15 is 10.8 inches wide. The third part of the rating is the aspect ration, i.e., the height of the tire from the mount to tread, expressed as a percentage of the width of the tire. In this case, the third part of the rating is 75, and this signifies that the tire bearing such a rating has three-fourths, or 75 per cent its width as height. The final part of the example rating we have considered is a combination of two bits of information. The alphabet R in R15 signifies that the tire is actually a radial tire, and the number 15 is the measure of the diameter of the radial tire. When you know how to interpret the ratings of a tire, you can ensure that you would not go wrong while trying to pick up a set of new tires for your automobile.

Tire Speed Rating

Since the invention of the automobile, many drivers have been concerned with one thing – speed. Understanding how fast your vehicle can go will help you have a more enjoyable and safer driving experience. But, to get a full understanding of how fast your vehicle can drive, you must have a firm understanding of tire speed ratings.

Speed ratings become an important consideration if you need to look for tires for your sports cars which would be running at speeds in excess of 100 miles an hour pretty frequently. It does not really get counted as a real concern if you just need the tires for routine driving in your passenger cars. Some tires are specially made to perform at unusually high speeds, and manufacturers of such tires make it a point to include an indication of the safe limits of driving speeds in the speed ratings of the tire. The inner sidewall of your automobile’s tires might bear another rating, called the Uniform Tire Quality Grading rating, abbreviated as UTQG. This rating carries important information about the performance and quality of the tire as determined by standard testing procedures that check parameters such as traction and the tread’s wear and tear.

Many casual drivers do not even know that every tire is rated to travel at a maximum speed. This tire speed rating is printed on the rim of each tire that you have ever purchased, and you may have never noticed it. Tire manufacturers as Firestone, Goodyear, Michelin put their products through strenuous testing, including speed testing. Depending on the intended use of a tire, a manufacturer will ensure that it can be safely used up to and appropriate top speed. They perform this test by spinning the tire against a weighted metal drum that represents the weight of a vehicle.

What Do You Need To Know About Tire Speed Ratings?

Understanding tire speed ratings is simple, and if you ever change the cheap tires on a vehicle you should pay close attention to them. The speed rating is usually marked after the tire size, which is printed in the rubber around the rim of each tire.

Let’s take, for example one of the most popular tire size – P225/60R16. On your tire these numbers would be followed by a two digit number and a letter – 87R, for example. The 87 it denotes the tires load index or the amount of weight that it can safely carry. The R denotes the tire’s speed rating.

The speed rating of a tire is usually represented by a letter L through Z. These numbers correspond to a maximum speed. For instance, L refers to a maximum speed of 85 mph or 120 km/hr. Y refers to a maximum speed of 186 mph or 300 km/hr. Here is a table with some of the most common tire speed ratings.

tire speed rating
Tire Speed Rating

It is important that you match your tire’s speed rating to your vehicle. Most manufacturers recommend that you choose a tire that is at least one great higher the maximum speed of your vehicle.

Can You Downgrade To A Lower Speed Rating?

Buying a new tire that has a lower speed rating than that which is recommended is not a good idea. First of all, it is a big safety hazard. If for any reason your car accelerates to its maximum speed, a lower rated tire may fail. It may cause a blowout and an accident.

On top of this, many automobile insurance providers will not provide money for an accident if a vehicle is using an incorrect tire speed. Unless you plan on equipping a downgraded tire on your own, you will probably have some trouble finding a garage that will put them on for you as many mechanics will refuse to do so.

What Do You Need In A Tire As Far As Speed?

Most drivers do not need to worry about using higher rated tire speeds. For the most part, you need to have a tire that is capable of reaching a speed higher than your vehicle’s maximum speed. This will ensure that you never cause a tire to go faster than it is rated for.

Some of the most common tire speed ratings are R – 106 mph, S – 112 mph, and T – 118mph. If you drive a sports car, you may find it necessary to purchase tire ratings like V – 149 mph or even Z, which denotes a tire capable of driving more than 149 mph.

Do not neglect to pay attention to your tire speed ratings. When you’re searching for new tires, always keep technical specifications at the front of your head.