Choosing the right tire speed rating is a key part of buying new tires. If you’re comparing an S vs T speed rating, you need to know what each one means for your driving. This guide breaks down the differences in simple terms, so you can pick the right tire safely and confidently.
S Vs T Speed Rating
Speed ratings are not just about top speed. They indicate the tire’s overall performance capability, including its handling and heat resistance. An S-rated tire and a T-rated tire are both common, but they serve slightly different purposes.
What is a Speed Rating?
A speed rating is a letter code on your tire’s sidewall. It shows the maximum speed the tire can safely maintain over time. This rating is part of the service description, which you’ll find right after the tire size. For example, a tire marked “P205/55R16 91T” has a speed rating of “T.”
The system was developed in Europe to give drivers a standardized measure of performance. Higher ratings often mean the tire has a more robust construction and better materials. This helps it handle the extra stress from heat and force at higher speeds.
Decoding the “S” Speed Rating
An S speed rating means the tire is certified for speeds up to 112 miles per hour (180 km/h). This is one of the more common ratings you’ll see on the market today.
- Maximum Speed: 112 mph (180 km/h).
- Typical Use: Found on many family sedans, minivans, and older model cars.
- Performance Level: Designed for everyday driving at legal highway speeds. It offers a good balance of comfort and durability.
If your vehicle’s original tires had an S rating, it’s generally safe to replace them with S-rated tires again. However, you should always check your owner’s manual for the manufacturer’s specific recommendation, as sometimes they suggest a minimum rating.
Decoding the “T” Speed Rating
A T speed rating is one step above S. It indicates a tire can handle speeds up to 118 mph (190 km/h). This small increase in speed capability often reflects a slight upgrade in performance.
- Maximum Speed: 118 mph (190 km/h).
- Typical Use: Very common on modern sedans, crossovers, and smaller SUVs.
- Performance Level: Provides marginally better handling and heat dissipation than an S-rated tire, making it a popular OEM choice for newer vehicles.
Many car makers now fit T-rated tires as standard because they offer a bit more of a safety margin. The construction is often a little more responsive without sacrificing too much in terms of ride comfort or treadlife.
Side-by-Side Comparison: S vs T
Let’s put the key facts next to each other to make the differences clear.
- Speed: S = 112 mph. T = 118 mph. The difference is 6 mph at the absolute maximum.
- Vehicle Fitment: S is common for older models and basic vehicles. T is extremely common for modern mainstream cars and crossovers.
- Performance Feel: T-rated tires may feel slightly more stable during quick maneuvers or on longer highway trips due to their enhanced construction.
- Availability: For many tire sizes, T-rated options are now more prevalent than S-rated ones, as it’s become a default for many manufacturers.
The core takeaway is that while T is technically a higher performance rating, the practical difference for legal, everyday driving is very minimal. Both are suited for typical highway use.
Can You Mix or Substitute These Ratings?
This is a critical safety question. Here are the basic rules you should follow.
- Check Your Owner’s Manual: Always look here first. The vehicle manufacturer states the minimum speed rating required for your car’s weight and performance.
- Never Downgrade: If your car came with T-rated tires, you should not install S-rated tires. The lower-rated tire may not handle the stresses your vehicle can create, leading to premature failure.
- Upgrading is Usually Okay: If your car came with S-rated tires, moving to T-rated tires is generally acceptable. The tire can handle more speed and stress, so it’s a safe switch. However, the ride quality might change slightly.
- Never Mix on the Same Axle: You should never put tires with different speed ratings on the same axle. This can cause unpredictable handling. For all-wheel-drive vehicles, mixing ratings can even damage the drivetrain.
When in doubt, consult with a professional tire technician. They can help you match the correct tire to your specific vehicle and driving needs, ensuring you stay safe on the road.
Impact on Ride Comfort and Tread Life
Many drivers wonder if a higher speed rating means a harsher ride or less mileage. The relationship isn’t always straightforward.
Often, a T-rated tire might use a slightly different rubber compound or internal structure than an S-rated version of the same model. This can sometimes lead to a firmer ride feel, but modern tire engineering has minimized this. The difference in daily driving is often unnoticeable.
For tread life, the softer compounds in high-performance tires wear faster, but the jump from S to T is not a jump into high-performance territory. Both are considered all-season touring ratings. You likely won’t see a significant difference in wear between them, as driving habits and maintenance have a much bigger impact.
How Weather and Driving Conditions Affect Your Choice
Your local climate and typical roads play a role too. Both S and T rated tires are available in all-season, touring, and sometimes even grand-touring categories.
- All-Season Tires: Most S and T rated tires fall into this category. They are designed for year-round use in areas with mild winters.
- Winter/Snow Tires: If you buy dedicated winter tires, you will see S or T ratings on them as well. The speed rating remains important, but winter tires prioritize traction in cold weather over extreme speed.
- Wet Weather Handling: A T-rated tire might have marginally better aquaplaning resistance due to its tread design, but this is model-specific, not rating-specific. Always look at independent tire tests for wet braking scores.
For severe winter conditions, the tire’s rubber compound and tread pattern (look for the Three-Peak Mountain Snowflake symbol) are far more important than the small difference between an S or T speed rating.
Making the Right Decision for Your Vehicle
Follow this simple step-by-step process to choose correctly.
- Locate your current tire size and speed rating on the sidewall of your tire.
- Check your vehicle’s owner’s manual for the manufacturer’s recommended speed rating.
- Decide if you want to match the original equipment (OE) tire exactly or are considering an upgrade.
- When shopping, filter your search by your tire size and the required speed rating (e.g., 91T).
- Compare tire models within the correct speed category, looking at reviews for wet braking, noise, and treadwear.
- If you are still unsure, call a tire shop and give them your vehicle make, model, and year. They can confirm the appropriate ratings.
Remember, the speed rating is a safety certification. It’s not a suggestion. Choosing a tire that meets or exceeds your vehicle’s requirements is non-negotiable for safe operation.
Frequently Asked Questions (FAQ)
Is a T rated tire better than an S?
Technically, yes. A T-rated tire has a higher maximum speed capability (118 mph vs. 112 mph) and often features a construction that can handle slightly more stress. For daily driving, the difference in “better” might not be noticeable unless you push the vehicle hard.
Can I use T tires instead of S?
In most cases, yes. Upgrading from an S to a T speed rating is usually safe and acceptable, as you are fitting a tire that exceeds the original specification. Just ensure the load index is also correct.
What happens if I use a lower speed rated tire?
Using a tire with a lower speed rating than your vehicle requires is dangerous. The tire may overheat, wear out extremely quickly, or even fail during high-stress driving like emergency maneuvers or sustained highway speeds. It can also void your vehicle’s warranty.
Do S and T ratings affect fuel economy?
The speed rating itself does not directly cause a change in fuel efficiency. However, tires with different ratings may have varying rolling resistance based on their tread design and compound. Always check the tire’s fuel efficiency grade if that is a priority for you.
Where can I find my tire’s speed rating?
Look on the sidewall of your tire. The speed rating is the last letter in the service description, which follows the tire size. For example, in “P215/60R16 94T,” the “T” is the speed rating. It’s sometimes easy to miss if you don’t know what your looking for.
Understanding the S vs T speed rating helps you make an informed, safe purchase. While the difference seems small on paper, adhering to the correct rating for your vehicle is a fundamental part of tire safety. Always prioritize matching or exceeding your car manufacturer’s specifications, and you’ll enjoy a secure and comfortable drive for miles to come.