We get a lot of questions on tire speed ratings, what they mean, and how they change what tire you need, so we figured to produce a guide on it.
What Are Tire Speed Ratings?
Here’s a simple explanation of the tire speed rating chart:
Also known as the speed symbol, tire speed ratings are recommendations that indicate the maximum speed capability of a specific tire.
Car tire’s speed ratings range from ‘A1’ to ‘(Y)’ — ‘A1’ being the slowest, and ‘(Y)’ being the fastest (see chart below). The reason for a speed rating is to have a safety standard in place for tire manufacturers.
Typically the speed rating chart goes in alphabetical order in accordance with speeds from lowest to highest. However, you will notice H does not come after G. This is because the original three letters for speed ratings were H, S, and V.
When the full speed rating chart was put into effect H already had a designated speed of 130 MPH. That is why you will see H much higher on the chart.
You can find these different speed ratings listed typically as the last letter in the tire service description. To find the service description check the sidewall of your tire and you will see a series of numbers that looks like this: 226/65R17 99V
The letter V is the speed rating all tires are required to have this description on at least one side of the sidewall.
Some common tire speed ratings for high-performance tires are:
While winter tires have a wide range of speed ratings like:
Touring/All-season tires typically have mid-range speed ratings like:
All-terrain tires sometimes have slightly slower speed ratings like:
By now you should be getting the picture. And just because some tires (like the BFG All-Terrain KO2) have a lower speed rating doesn’t mean that they can’t be driven at highway speeds. It just means that the tire is not designed to perform at higher speeds than designated.
On tires that have a Y speed rating of up to 186 MPH (300 kilometers per hour), you might also see ‘ZR’ printed somewhere in the size designation (the three-number tire size).
Although ‘ZR’ isn’t listed as a speed rating on the chart, it’s possible to see tires that have a ZR rating in their tire size number, and that typically just means the tires can travel over 149MPH.
Here’s a quick video explaining speed ratings a bit more and what happens if you exceed the speed rating for your car or truck.
What Is A Good Speed Rating For A Tire?
You might think that the tires with the fastest speed ratings are the best, but it’s not true. A tire’s performance at high speeds isn’t everything.
Simply put, tires with higher speed ratings have harder rubber compounds, and typically thinner tire sidewalls (smaller aspect ratio), so they don’t provide good suspension to the car like softer (slower) tires give.
Don’t forget the tires are the only part of your suspension system that makes contact with the road.
Higher speed-rated tires typically have shorter sidewalls (see the middle tire number i.e. 225/65/R17) that can cause your rims to bottom out on bumps, while taller and slower tires improve ride comfort.
Also, think about tire composition. What’s in a tire?
Tires contain natural rubbers, steel belts/wires, fillers, and even curing systems, antioxidants, antiozonants, etc., and the culmination of all of these makes up what a tire is.
From a tire manufacturer’s perspective, there are a lot of steps that need to go right when making tires. Ensuring that a tire has the proper speed rating for how the tire is designed to perform is another step manufacturers have to include.
To determine what a good speed rating is will ultimately depend on the vehicle. Passenger car tires will typically have lower ratings than sports cars, and light truck tires will have even lower speed ratings than passenger cars.
A high-speed rating will be determined by how the manufacturer wants the tire to perform on certain vehicle applications, the higher this rating is the better traction it will provide at faster-operating speeds. The benefit to a lower rating is that it will be more comfortable and last longer, which is why you see high-performance options have such short tread life.
Which Is The Right Tire For My Car?
Vehicle owners: don’t forget, you can often find the recommended speed rating for your vehicle manufacturer’s tires by either checking the owner’s manual or take a glance inside the driver’s side door panel, where there will be a sticker placard with the vehicles tire description(it is typically yellow and red).
A good rule of thumb is don’t put tires on your car if they have a lower speed rating than what came on the vehicle’s original equipment tires. For example, if you have a sports car, you shouldn’t put some cheap all-season tires that are going to blow out when you get them up to carpool lane speeds.
I’ve also noticed that the longest-lasting tires typically don’t have ultra-fast speed ratings. For example, Michelin Defender tires offer a pretty unbeatable mileage warranty of up to 80 thousand miles while ultra-high speed rated tires like the Michelin Pilot Sport are only guaranteed for 45 thousand miles.
Part of this is because high-performance tires are driven more aggressively, and they also have thinner sidewalls/fewer silica fillers. Tread compound also definitely has something to do with it, but that’s a more complex matter.
When I would sell tires to customers oftentimes they would ask for a tire with a lower speed rating than is recommended. This would usually happen because lower-rated tires have higher mileage warranties. I would always explain that when you put a lower-rated tire on your vehicle they would wear out much faster.
It just goes to show that just because a tire has a high mileage warranty does not mean it’s the right tire for your vehicle.
What Is Tire Load index(Tire Load Rating)?
The maximum amount of weight that a tire can carry with a maximum amount of pressure. The higher the load index, the higher the weight capacity the tire can support at max psi.
The load index is one of the most important ratings on the tire. If you put a tire with a lower load index than what the vehicle manufacturer recommends, you are at risk of tire failure which could result in tread separation or a blowout.
Most tire retailers will not install a tire that has a lower load carrying capacity than what comes factory for the vehicle. However, they are those few and far between shops that will.
You can find information like recommended tire speed rating and tire load index for your car on the inside of your driver’s side doorjamb.
What Are UTQG Ratings?
Aside from speed ratings, tires also have UTQG ratings (uniform tire quality grade) created by the US Department of Transportation (National Highway Traffic Safety Administration). Think of it as standard versus metric. It was created to hold manufacturers accountable and keep drivers like yourself safe on the road.
The USA always has to have its take on the matter. That said, the UTQG rating breaks down specific tire models statistically on one chart, so it’s quite helpful when comparing tires.
UTQG ratings are extremely useful because they give you three specific ratings for traction, temperature, and treadwear. Each rated tire is also tested on a government-controlled test course to help determine its placement.
So for example:
Traction measure’s the tire’s ability to stop on wet surfaces. There are three traction ratings, from highest to lowest:
- AA (best traction)
- C (worst traction)
Traction ratings on an actual course are good because they consider cornering capability and factor it into the expected tread life. Remember no tire that is overinflated or underinflated will last according to its corresponding traction rating. Tire maintenance (like tire rotations) is also the key to long tire life.
There are three ratings for temperature resistance from best to worst:
- A (most temperature resistant)
- C (least temperature resistant)
Treadwear is measured using a numbering system from 100 to 1000.
Tires with a treadwear rating of 400 will last twice as long as tires with a treadwear rating of 200.
One could say UTQG ratings are a bit more scientific than just a simple and comprehensive speed rating, but ultimately it’s good to know as much information as possible when it comes to the new tires on your sedan, coupe, or any other car or truck.
My Final Thoughts On The Tire Speed Rating System
The tire speed rating system is a great tool that was created to ensure manufacturers are held accountable for claims on their tires. For instance, if you were sold a tire that could only travel at 50 MPH when you frequently drive on the highways between 60-80 MPH. You could end up crashing from losing control of your vehicle because the tires weren’t designed to perform at such high speeds.
That is an extreme scenario, but still, it wouldn’t be your fault or the sales associates because manufacturers would be allowed to build their tires with no regard to speed.
For this reason, it is important for you to know what a speed rating is and why it is so crucial in your tire buying process!