Have you ever wondered what all the numbers and letters on your car’s tires represent?
From the size to the speed rating, each character on a tire serves a specific purpose. But, I bet you didn’t know just how much info your tire actually holds.
We’ll dive into the details of tire markings and what they mean. I promise by the end of it you’ll be reading tires-like quotes on the wall.
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Table of Contents
- Brand And Model
- Tire Size
- Load Index And Speed Rating
- Treadwear, Traction, And Temperature Ratings
- Date Code
- Max Tire Pressure
- Wrapping Things Up
Brand And Model
The brand and model of a tire are usually prominently displayed on the sidewall, typically in large bold text in some easily recognizable font.
The brand name gives you an idea of the tire’s quality and reputation, while the model can help you understand the tire’s intended use, such as performance, all-season, or off-road.
This information is helpful in making sure that all four tires match.
Here’s a list of some common tire types:
All-Season Tires – A/S
- Designed for year-round use in moderate weather conditions, providing a balance of traction, handling, and durability.
Mud and Snow Tires – M+S
- Designed to provide the best traction in muddy and snowy terrain with deep tread blocks.
Winter Tires – Snowflake Symbol
- Designed for use in cold and snowy weather conditions, providing enhanced grip on ice and snow.
Summer Tires –
- Designed for use in warm weather conditions, providing increased performance and handling in dry and wet conditions.
All-Terrain Tires – A/T
- Designed for use on and off the road, providing good traction in a variety of conditions.
Mud Tires – M/T
- Designed for use in muddy off-road conditions, providing maximum traction in deep mud and other challenging terrains.
Performance Tires – P
- Designed for high-performance vehicles, providing enhanced handling and responsiveness at high speeds.
Touring Tires – T
- Designed for long-distance driving and comfort, providing a smooth and quiet ride.
Run-Flat Tires –
- Designed to allow you to continue driving for a limited distance after a puncture or blowout, providing increased safety and convenience.
Low-Rolling-Resistance Tires –
- Designed to improve fuel efficiency by reducing the amount of energy needed to move the vehicle.
R Racing tires –
- Designed for use in motorsports, providing maximum grip and performance at high speeds.
Additionally, knowing the brand and model of your tire can help you more easily find replacements or upgrades when needed.
Why do you want all four tires to match? To ensure optimal performance and safety.
Tires are designed by the manufacturer to work as a complete set, mixing brands and tire types will not give the desired results of any one specific tire.
Tire Size
The tire size is the most important number on the tire, and it’s typically found on the sidewall. If you’ve ever bought tires you may have come across this number when shopping.
The format is usually in this order: width, aspect ratio, and diameter.
For example, a tire with the marking 225/45R17 has a width of 225 millimeters, an aspect ratio of 45 percent, and a diameter of 17 inches.
Width and diameter are easy to understand but you may be asking “what is aspect ratio?” Good Question.
The aspect ratio number is actually the height of the tire. So why isn’t it called height?
That’s because the height of tires is represented as a percentage of the width of a tire. Hence the name aspect ratio because it is the ratio of height to width.
So the height of our example tire is 45% of 225.
Why is it done this way? Who knows but it’s the standard.
Understanding your tire size is crucial for finding the right replacement tires for your vehicle.
Load Index And Speed Rating
The load index and speed rating are the next important numbers to consider when reading any tires for your vehicle.
The load index indicates how much weight a tire can support, while the speed rating indicates the maximum speed a tire can safely handle.
Load index is very important on work vehicles that haul like work trucks and vans, while speed ratings are important for performance vehicles like race cars.
These numbers are typically found at the end of the tire size markings.
For example, a tire with the marking 225/45R17 94V has a load index of 94, which can support 1,477 pounds, and a speed rating of V, which means it can safely handle speeds up to 149 mph.
Here are all the load index ratings and their corresponding maximum load capacity for passenger car tires:
| Load Index | Maximum Load Capacity (lbs) |
|---|---|
| 71 | 761 |
| 72 | 783 |
| 73 | 805 |
| 74 | 827 |
| 75 | 853 |
| 76 | 882 |
| 77 | 908 |
| 78 | 937 |
| 79 | 963 |
| 80 | 992 |
| 81 | 1019 |
| 82 | 1047 |
| 83 | 1074 |
| 84 | 1102 |
| 85 | 1135 |
| 86 | 1168 |
| 87 | 1201 |
| 88 | 1235 |
| 89 | 1279 |
| 90 | 1323 |
| 91 | 1356 |
| 92 | 1389 |
| 93 | 1433 |
| 94 | 1477 |
| 95 | 1521 |
| 96 | 1565 |
| 97 | 1609 |
| 98 | 1653 |
| 99 | 1709 |
| 100 | 1764 |
| 101 | 1819 |
| 102 | 1874 |
| 103 | 1929 |
| 104 | 1984 |
| 105 | 2039 |
| 106 | 2094 |
| 107 | 2149 |
| 108 | 2205 |
| 109 | 2271 |
| 110 | 2337 |
| 111 | 2403 |
| 112 | 2469 |
| 113 | 2535 |
| 114 | 2601 |
| 115 | 2679 |
| 116 | 2756 |
| 117 | 2833 |
| 118 | 2910 |
| 119 | 2998 |
| 120 | 3086 |
| 121 | 3197 |
| 122 | 3307 |
| 123 | 3417 |
| 124 | 3527 |
| 125 | 3638 |
| 126 | 3748 |
| 127 | 3858 |
Speed Rating
The speed rating indicates the maximum speed at which a tire can safely operate. Here are the speed rating letters and their corresponding maximum speed:
- N: 87 mph
- P: 93 mph
- Q: 99 mph
- R: 106 mph
- S: 112 mph
- T: 118 mph
- U: 124 mph
- H: 130 mph
- V: 149 mph
- Z: Above 149 mph
- W: 168 mph
- Y: 186 mph
- (Y): Above 186 mph
Treadwear, Traction, And Temperature Ratings
The treadwear, traction, and temperature ratings are also important numbers to consider when selecting tires but to a lesser extent.
Treadwear Rating
The treadwear rating indicates how long a tire is expected to last compared to a reference tire with a rating of 100. For example, a tire with a rating of 200 is expected to last twice as long as the reference tire.
The treadwear rating is expressed as a number, rather than a letter.
Traction Rating
The traction rating indicates a tire’s ability to stop on wet roads. Here are the traction rating letters and their corresponding performance:
- AA: Best
- A: Better
- B: Good
- C: Acceptable
Temperature Rating
The temperature rating indicates a tire’s ability to dissipate heat. Here are the temperature rating letters and their corresponding performance:
- A: Best
- B: Good
- C: Acceptable
These ratings are usually found in small letters on the sidewall of the tire.
Date Code
The DOT Code on your tire is a combination of letters and numbers, with the most crucial part being four digits that indicate the tire’s manufacturing date.
For instance, if the four digits read “1321”, it means the tire was produced during the 13th week of the year 2021.
Knowing tire manufacturing dates is important because tires DO go bad after a while. Rubber doesn’t last forever and it does degrade over time regardless of use.
There are many dangers of aging tires including the possibility of potential life-threatening disaster.
Max Tire Pressure
So when you’re checking out the maximum inflation rating on your tires, you’re going to see it written in both pounds per square inch (psi) and kilopascals (kPA).
But don’t go inflating your tires to the max, because that’s not always the recommended pressure. It’s only the max the tire can withstand safely.
Instead, check your owner’s manual or the tire information label on the driver’s side doorjamb to find out the right pressure for your tires.
Wrapping Things Up
Understanding the numbers and letters on your tires is important for ensuring your safety on the road.
From tire size to load index, each marking serves a specific purpose in determining the right tires for your vehicle.
By knowing what each number and letter means, you can make an informed decision when selecting replacement tires for your car.
Or maybe just enough to impress your friends at the tire counter.
We might receive commissions if you click on our links and sign up/make purchases. However, please know this does not impact our reviews and comparisons. We try to keep things fair and balanced to help you make the best choice for your needs. Thanks