What Are Tire Speed Ratings?

If you’re new to the world of tires, you may not have realized that they have speed ratings. These are important, as they indicate the optimal speed that a tire can maintain safely over time (in other words, it’s the fastest that a tire can handle before it no longer performs as designed). The higher the speed rating, the better control and handling you’ll have over the tire at high speeds.

The tire speed rating system was developed to help control the performance of tires at standardized speeds. Each tire is given a letter rating, from A (3mph) to Z (above 186mph), to designate the top speed at which it’s allowed to travel.

The team at Carlisle TyrFil is very familiar with tire speed ratings and is committed to ensuring that our customers have the right tires for their intended application. Get in touch with our helpful team today to further discuss the speed rating that is most appropriate for your needs.

Why Were Tire Speed Ratings Developed?

The speed rating system currently in use was originally developed in Europe as a means of controlling the safe performance of tires at standardized speeds. When it was first developed, the top speed rating possible was known as the ‘Unlimited V’ category that covered tires rated over 130mph.

With the production of bigger and better tires came the need to regulate performance at even higher standardized speeds to further ensure safety. This led to the creation of the ‘Limited V’ category of 149mph, followed by the Z category we have today as the top speed rating.

How are Tire Speed Ratings Determined?

Tire manufacturers conduct various tests on their products, including a speed test, to determine the rating that the tire should ultimately receive.

It should be noted that the recommended speed for safe and optimal tire performance may actually be lower than the maximum speed as indicated by the speed rating. It’s essential that you adhere to the vehicle manufacturer’s recommended speed and consider external factors (such as tire condition, inflation level, whether you’re carrying any extra weight, road surfaces, and the weather) to ensure that you arrive at your destination safely.

Where do I Find the Tire Speed Rating?

Typically, you can find your required tire speed rating in several places, including the owner’s manual, driver’s side door jamb, glove box door, and gas tank hatch. Finding the speed rating of a tire is also relatively easy thanks to recent standardization changes — the speed symbol and load index are now incorporated as part of every tire’s service description on the sidewall (excluding the ‘Unlimited ZR’ category). The speed rating will be the last item in the character sequence.

Let’s use the description of 205/60R15 91V as an example.

  • 205 refers to the width of the tire (in millimeters)
  • 60 refers to the aspect ratio
  • R refers to the radial construction
  • 15 refers to the rim diameter (in inches)
  • 91 refers to the load index
  • V refers to the speed symbol

Can I Use Tires With a Higher Speed Rating?

Yes, there is absolutely no problem at all using higher speed-rated tires on your vehicle or machine. In fact, this can actually improve your cornering response, stopping power, and steering abilities.

It should be noted that you cannot use tires that are lower than the recommended speed rating of your machine, as this can lead to all sorts of safety concerns. It’s also important that you look at your speed rating and load rating together to ensure maximum safety.

Can I Use Tires with Different Speed Ratings?

Whilst nothing is stopping you from doing this, it’s not recommended that you mix and match tires with different speed ratings. This is why, when tires are replaced, they should always be done in sets of four.

If, however, you must use tires with different speed ratings, it should be noted that the limit on the lowest-rated tire is your fastest speed. Do not exceed this.

Ensure that you have the Correct Tire Speed Rating with Carlisle TyrFil

It’s not just cars and motorbikes that need to be concerned with tire speed ratings — even heavy machinery must be fitted with appropriately rated tires to ensure the safety of the operator (not to mention a more comfortable ride). The good news is that the team at Carlisle TyrFil is very experienced when it comes to speed ratings for the tires we work with. Get in touch with our team today if you require more advice.


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