Tires play a massive role in any vehicle. They are responsible for steering, accelerating, and braking, so they need to be with the correct specification.
When we talk about specs on a tire, we usually cover a wide range of things like size, load index, and speed rating. These work in combination to provide the best possible performance on any car. Manufacturers fit the tires with the required specifications, and while there is some room for changes in some areas, for others, it’s not recommended.
While tire size is something you can change, other aspects like the speed rating shouldn’t be changed too much. To get you up to speed, pun intended, I’ll explain what this rating is and why it’s important to pay attention to it.
H vs V Tires
The speed rating is what determines how fast a tire can go before it tears itself apart. With this in mind, in this comparison, the V-rated tire will have an edge.
H-rated tires can handle a maximum speed of 130 mph, while V-rated ones are good for up to 149. As a result, the second tires are the ones you’d fit on a faster vehicle, capable of reaching those speeds.
What is a Speed Rating?
Not all tires are created equal, and some are better than others in certain areas. Speed is one of them, which is why tire manufacturers have different ratings even within the same models.
A tire’s speed rating is the maximum safe speed at which it can operate. They undergo rigorous tests to ensure that they can withstand the forces and heat in the real world.
Since the speed rating was first introduced in the 60, the table had only 3 letters, S, H, and V. As tires evolved, so did the table, and today it has all the letters of the alphabet, almost.
Under the A rating, there are 8 sub-ratings with increasing increments. After that, things continue from B to Y, and you’ll notice that I and Z are missing and H isn’t in the right spot.
The Z is reserved for the last 3 speed ratings, which are the highest and are designated as ZR, along with the actual rating. H is several places up because, in the early days, that was the highest speed a tire could be rated. As technology improved, tires could withstand higher speeds, and it was counterproductive to change the ratings, so H stuck near the higher end of the spectrum.
Initially, the speed ratings were measured in km/h, and the numbers are nice and round, but with the imperial system, it may seem weird.
In terms of reading the rating, things are very simple. The speed rating is the letter that comes after the load index, after the tire’s dimensions. So, if the tire’s sidewall reads 205/55R16 91V, it means it’s a V-rated tire.
For the most part, the speed rating is tied with the size, and you may not find tires with identical dimensions but different speed ratings. With that said, there are exceptions to this “rule.”
Speed Rating Chart
|Speed Rating||Speed in km/h||Speed in mph|
Why do Tires Have Different Speed Ratings?
When manufacturers make tires, they make different models, so they are expected to be slightly different.
A tire’s durability starts from the inside and the internal construction. The rotational forces at higher speeds are more than enough to tear the tire from the inside, so sturdier construction is needed.
Next up is the compound, which will have to deal with the same forces. In addition to that, friction is also present, and the more friction a tire has, the more heat will be generated. The rubber compound on these tires is generally a bit softer but better at dissipating the heat, so higher-rated tires can survive being driven at 300+ km/h.
Having a high-speed rating doesn’t mean that the tire should only roll at higher speeds and remain intact. It also means that it should be able to deliver excellent performance because, let’s face it, a Maxima won’t have the highest rated tire fitted. For the most part, the rubber compound is responsible for delivering grip and traction when you’re driving at maximum speed.
How Is the Speed Rating Determined?
Things start off theoretically even before the tires are manufactured. Based on previous tests and research, companies can “guess” the maximum safe speed for a tire. Once the production process begins, they start with the testing to verify the earlier claims.
The test consists of spinning the tire against a drum and applying a load. It’s a realistic load aimed at testing the tire with the most realistic scenarios. Things start with speeds of 40 km/h or almost 25 mph below the target and get increased throughout the testing. For a tire to pass the test, it needs to remain usable after 10 minutes at that speed.
Some manufacturers, mostly the premium ones, take things to the next level. They will continue increasing the speed until the tire fails. This gives them an insight into how durable a tire is.
Up until this point, the testing I explained is based on the ECE requirements. The Economic Commission for Europe dictates that a tire should be tested for 10 minutes, and it gets a pass if it remains usable after that.
On the other hand, tires are tested based on the Society of Automotive Engineers. The SAE standard is one where a tire is tested for 1 hour at maximum speeds with the temperature set at 100 degrees.
What Is the Difference Between an H and a V-rated Tire?
Powered with the knowledge I outlined, you can probably guess the difference between these two tires.
Tires with an H-rating are designed for speeds up to 130 mph or 210 km/h. On the other hand, V-rated tires are good for slightly higher maximum speeds of 240 km/h or 149 mph. The sum of this is that V-rated tires are better because they can handle higher speeds.
It may seem like the difference isn’t massive, but almost 20 mph isn’t something you should ignore, regardless if you ever drive at that limit.
How to Determine the Correct Speed Rating of My Tires?
This isn’t something that you should determine by yourself because car manufacturers do that for you. Some people say that it’s okay to step down a few ratings if you never drive that fast, but it’s not something that I’d recommend.
My 92 Corolla came with T-rated tires from the factory, which are good for speeds up to 118 mph. Realistically, the tiny 1.3 carbureted engine can barely go over 100, so I can just get an R-rated tire and call it a day, right?
While that is true, it’s still not something I’d do. Even though my car needs a downhill to get to triple-digit speeds, going for a lower-rated tire is still something that I wouldn’t do. The tire can survive those speeds, but imagine driving at the limit for several hours.
Regardless of the rating, the tire can still fail, which is more likely to happen as the tire ages. Going for a T-rated tire ensures that I have a safe driving experience, even though I rarely even go over 80 on the highway.
Where Else Will I Notice Differences With Tires With Different Ratings?
While there may be subtle differences in tires’ performance and refinement with different speed ratings, the biggest difference is longevity.
Tires designed for speeds of over 150 mph will have a softer compound, making them more prone to a quicker wear. This is the main reason why performance-oriented tires don’t come with a treadwear warranty, or then one they have is a third of touring tires.
Speaking of, grand touring tires, on the other hand, offering a longer treadwear warranty won’t have the highest speed rating in the industry.
Can I Mix Tires With Different Speed Ratings?
No, mixing and matching tires with different speed ratings is something that you should never do. This goes against everything I explained in the previous section.
Can I Get Tires With a Higher Speed Rating?
Sure, going for a higher speed rating isn’t something that will be a problem. To some extent, it may even give you peace of mind, knowing that you won’t be hitting the upper speed mark so easily.
If the top speed of your car is 120 mph, the manufacturer recommends H-rated tires for 130 mph, and you get V-rated ones for 149 mph, just means that you have more headroom.