What Are Tire Speed Ratings

Do you know how fast you can drive before your tires lose performance? Every tire design actually has its own upper limit of speed, after which you’ll start to lose control and handling. This is the tire speed rating, and all of your tires have their speed ratings displayed right on the sidewall.

It’s important to understand your speed ratings because exceeding the recommended limit puts both your tire performance and your own safety at risk. There are some unique quirks about how speed ratings are used, so here’s an overview of everything you need to know about your tires’ speed ratings.

Understanding Tire Speed Ratings

Tire speed ratings are determined through laboratory testing, as each unique tire model is put through trials of different simulated speeds and weight loads. After testing, that tire model is given a certified speed rating to indicate the maximum operating speed it can safely maintain over time.

The speed ratings by themselves do not indicate the total performance capability of a tire — such as braking power or cornering — but tell you how fast you drive before the tire’s performance suffers. Speed rating assumes a tire’s performance speed under “standard” conditions — which includes dry weather conditions, the recommended tire pressure level, and within the maximum carrying capacity or load range.

Tire speed ratings are assigned a letter from A to Z, ranging from 3 mph (5 km/h) to above 186 mph (300 km/h). When the rating system was originally developed in Europe during the 1960s, the highest speed rating was the unlimited “V” rating. This rating was for tires that had a maximum sustained speed of 149 mph (240 kph) or higher. Today, the V rating is used to indicate a maximum tire speed of 149 mph, but no higher, while W is used for a maximum of 168 mph, Y is for a maximum speed of 186 mph, and (Y) is for 186+ mph.

In general, speed goes up as the rating advances alphabetically — though there are some notable exceptions:

• In all tire speed rating charts, the letter “H” is out of regular order, as it is a hold-over from older rating systems. Instead of appearing after “G,” it falls between “U” and “V” and denotes a maximum speed of 130 mph.
• Tire speed charts also do not have “I,” “O,” or “X” speed ratings. Additionally, some speed rating charts don’t include the “P” rating.
• The “A” rating is actually broken down into multiple speed categories, each with its own number, ranging from A1 to A8.
• While industry standards require the “Z” rating for any tire with a maximum speed over 186 mph (300 kph), some tire speed ratings will include a “Z” rating for anything with a maximum speed over 149 mph. This special “Z” rating is separate from the regular speed rating, and will be inserted in the middle of the tire size description (right after the aspect ratio) changing the “R” to a “ZR”.

Here’s the full speed rating chart and the corresponding speed of each letter in miles per hour (mph) and kilometers per hour (km/h).

How to Read Your Tire’s Sidewall Information

You can find your tire’s speed rating by reading the code on the tire sidewall. The sidewall information is a combination of the tire’s size information and service description, which is its load index (load carrying capacity) and tire speed rating.

The speed rating is represented by a letter that directly corresponds to the tire’s max speed and will usually be the last item in the character sequence in the tire’s size code. However, if a tire is rated for all-season or winter driving, the speed rating may be followed by the M+S (mud and snow) and three peak mountain snowflake symbols, respectively.

For example, here’s a breakdown for a tire with the sidewall information of P215/65 R15 95H

P = Service description (passenger vehicle) 215 = Tire width (in millimeters) 65 = Tire aspect ratio (height to width) R = Tire construction (radial tire) 15 = Tire rim diameter code 95 = Tire load index rating H = Tire speed rating

You can also find the recommended tire speed rating for your vehicle in your owner’s manual, the driver’s side door jamb, glove box door, or gas tank hatch.

Tire Speed Rating Impact on Safety

While lab testing can’t simulate every conceivable condition your tires will experience, it is useful for determining a tire’s speed capability under controlled conditions. Driving at speeds over your tire’s speed rating makes your car harder to handle, will take longer to brake, and will lower the lifespan of your tires.

Driving at or under your tire’s speed rating is recommended to keep you, your passengers, and other drivers safe while on the road. A few more notes on safety:

• Your tire’s speed capacity may be lowered by damage or other factors such as over- or under-inflation, wear, excessive weight, or the vehicle’s general condition (such as tire alignment). If your tires aren’t in optimal condition, try to stay under their tire speed rating until you have them repaired or replaced.
• Speed ratings assume clear, dry driving conditions. Always reduce your speed in inclement weather, even if your tire is rated M+S for mud and snow or has the three peak mountain snowflake symbol for winter driving conditions.
• All new vehicles will come with original equipment manufacturer (OEM) tires that are meant to provide the intended performance. When it’s time to replace your tires, it’s recommended to install either OEM tires or — if using non-OEM tires — ones that closely match the performance specifications of your vehicle. For example, if your vehicle is rated for “T” speed tires, ensure that your replacement tires are either T rated, close to a T rating, or higher.
• When replacing your tires, make sure to install the same type of tire to each wheel position for optimum safety and performance. It’s not recommended to mix different tire speed ratings, and if you’re driving an all-wheel drive vehicle, you need to replace all four tires at the same time with the same type of tire.

Tire Speed Rating Influence on Performance

Aside from safety, tire speed ratings indicate a tire’s capacity to maintain ride comfort, wear, and cornering ability at higher speeds. Tires with higher speed ratings will often offer better handling and responsiveness at top speeds.

Depending on your vehicle’s specifications, if you enjoy spirited driving — and drive in areas with higher speed limits — investing in higher-rated tires can significantly enhance your car’s performance and overall driving experience. Just remember that you will need to lower your vehicle’s top speed if you install tires with lower speed ratings.

Industry Standards and Regulations

Tire speed ratings are used by the U.S. Department of Transportation and tire manufacturers. In some regions, there is a legal requirement to have tires with a speed rating equal to or higher than your vehicle’s intended top speed. Failing to comply with these regulations can result in fines or penalties.

If your vehicle comes equipped with high-performance tires, replacing them with lower speed rated tires might void your manufacturer’s warranty. Always check your vehicle’s owner’s manual or consult with a certified automotive professional when you’re thinking of changing out your tires.

Choosing the Right Speed Rating for Your Vehicle

Here’s a quick overview of some common vehicle types and the generally recommended tire speed ratings.

• Check Your Vehicle’s Specifications: Always refer to your owner’s manual or consult your manufacturer’s recommendations for the tire speed ratings appropriate for your vehicle. While you could choose a tire with a higher speed rating, it’s generally not recommended to install tires with lower speed ratings.
• Consider Your Driving Habits: Think about your typical driving scenarios and what will best meet your needs. Do you primarily drive on highways and drive at higher speeds? Is your car designed to travel at higher speeds? If so, then it could be worth investing in a set of tires with higher speed ratings.
• Adjust Your Speed to Driving Conditions: The speed rating is meant for controlled, ideal conditions. You should always check the conditions of your tires and vehicle and lower your top speed if you detect any level of wear or damage. Over- or under-tire inflation levels, extra vehicle weight, poor road surfaces, and inclement weather will lower the maximum safe speed for your tires.
• Consult the Experts: If you’re unsure whether certain tire speed ratings are appropriate for your vehicle, contact certified automotive professionals who can guide you based on your vehicle, driving habits, and local conditions.
• Explore Your Options: See what’s available for options and what will best fit your needs and budget. If you’re looking for information on specific tire brands you can always search by vehicle, tire size, or brand on the VIP website.

Frequently Asked Questions (FAQs)

How do I know the right speed rating for my tire?
Check your vehicle’s owner’s manual or the placard on the driver’s side door for recommended tire speed ratings. Match or exceed the manufacturer’s recommended rating to ensure safety and performance. Remember that off-road conditions, inclement weather, and tire wear will reduce your tire’s maximum speed rating.

What is the speed index on a tire?
The speed index is a letter on a tire’s sidewall that indicates the maximum speed a tire can safely travel. For example, a tire with an “S” rating is safe up to 112 mph. Always choose a tire with a speed index that meets or exceeds your vehicle’s specifications to ensure optimal performance and safety. Check your vehicle’s manual or consult a certified automotive professional if you’re unsure.

Can I mix tires of different speed ratings?
Mixing tires of different speed ratings can negatively affect your vehicle’s handling, stability, and overall performance, leading to unsafe driving conditions. Always follow your vehicle manufacturer’s recommendations for tire speed ratings, and ideally, use tires with matching ratings on all wheels. If you need to replace a tire, ensure the new one matches the speed rating of the others.

What’s the highest tire speed rating?
Currently, the highest speed rating for tires is (Y), which indicates a maximum speed that exceeds 186 mph (300 km/h). Tires rated for speeds above 186 mph will also be rated with a “Z” in the tire construction section of the sidewall. These high-speed ratings are typically found on tires meant for ultra-high performance vehicles or exotic sports cars.