How Are Tires Rated? | Sidewall Codes Made Clear

Tires are rated by size, load index, speed symbol, UTQG grades, and date code, all printed on the sidewall.

Most drivers hear the word “rated” and think a tire has one simple score. It doesn’t. A tire carries a stack of ratings, marks, and grades that tell you whether it fits your wheel, how much weight it can carry, how fast it is built to run, and how it compares with other passenger tires in treadwear, wet traction, and heat resistance.

That’s why the sidewall matters so much. Once you know the order of the numbers and letters, the code stops looking random. You can tell whether a tire is a safe match for your car, whether two tires are mismatched, and whether a bargain tire is cheap for a reason or just priced well.

A good way to read it is to split the sidewall into four parts:

• Fitment: section width, aspect ratio, construction, and rim diameter.
• Workload: load index, load range on some tires, and inflation limit.
• Performance grades: speed symbol plus UTQG treadwear, traction, and temperature on many passenger tires.
• Age and traceability: the DOT code, including the week and year of manufacture.

How Are Tires Rated? From Fitment To Grip Grades

Start with the main size string, such as P225/50R17 94V. Each piece answers a different question. The “P” marks a passenger tire in the U.S. system. “225” is the width in millimeters. “50” is the sidewall height as a share of the width. “R” means radial construction. “17” is the wheel diameter in inches. Then the service description appears: “94V” means load index 94 and speed symbol V.

The service description gets missed all the time. That’s a mistake, since it tells you how much weight each tire can carry and the speed category it was built for. When you replace tires, the safe move is to match the vehicle placard and owner’s manual, then match or exceed the original load index and speed symbol unless the vehicle maker allows a different setup.

After that, scan the UTQG line. On many passenger tires sold in the United States, you’ll see a treadwear number plus traction and temperature grades. The federal grading rule applies to passenger car tires with some carve-outs, and NHTSA’s tire safety ratings page lays out the system in plain language.

Here’s the plain-English read on those grades:

• Treadwear: a comparative number. A tire graded 200 should last about twice as long as a control tire graded 100 on the government test course.
• Traction: AA, A, B, or C for wet straight-line braking on test surfaces.
• Temperature: A, B, or C for heat resistance under test conditions.

Those marks help, but they are not a full report card. UTQG does not tell you snow grip, hydroplaning resistance in every condition, ride comfort, road noise, or cornering feel. That’s why a tire with a higher treadwear grade is not always the better buy for every car or every driver.

Sidewall Mark	What It Means	Why It Matters
P	Passenger-tire designation	Helps separate passenger sizing from LT and other formats.
225	Section width in millimeters	Must suit the wheel width and vehicle spec.
50	Aspect ratio	Shapes sidewall height, ride feel, and wheel protection.
R	Radial construction	Shows the tire’s build type.
17	Rim diameter in inches	Must match the wheel exactly.
94	Load index	Tells the tire’s load capacity at the rated conditions.
V	Speed symbol	Shows the speed category tied to the load index.
300	UTQG treadwear grade	Compares wear rate against a control tire.
A or AA	UTQG traction grade	Shows wet braking grade, not cornering grip.
A, B, or C	UTQG temperature grade	Shows heat resistance under test conditions.
DOT 2525	Built in week 25 of 2025	Lets you check age before buying or fitting.

Tire Ratings On The Sidewall Still Need Context

A treadwear grade is useful, but it’s not a mileage promise. The federal test compares tires on a controlled route, using a control tire graded at 100. Real roads, alignment, inflation, heat, and driving style can swing tire life by a wide margin. So a 500 treadwear tire may last a long time on one car and wear fast on another that is heavy, misaligned, or driven hard.

Traction grades trip people up too. In the U.S. system, traction is about wet straight-line stopping on asphalt and concrete. It does not rate dry braking, slalom grip, ice grip, or how the tire feels during a fast lane change. That’s why an all-season touring tire and a summer tire can share a strong traction grade while feeling nothing alike once the road gets hot and twisty.

Temperature grades are easier to grasp. They show how well the tire resists heat. Heat is hard on tires, and overload or low pressure makes it worse. In the federal rule, grade C meets the legal floor for passenger tires, while A and B mark stronger performance on the lab test. The federal UTQG standard also spells out which passenger tires sit outside this grading rule, such as winter-type snow tires and temporary spares.

Then there’s the date code. On one sidewall, the DOT serial ends with four digits. The first two digits are the production week. The last two are the year. A tire stamped 2525 was made in the twenty-fifth week of 2025. That does not mean the tire is bad. It does mean age belongs in the buying call, especially if the tire has been sitting in storage for a long stretch.

When You Compare Tires	Match This First	Use This As A Tie-Breaker
Replacing one damaged tire	Exact size, load index, and speed symbol	UTQG grade and build date
Replacing a full set	Vehicle placard size and service description	Treadwear and wet-traction grade
Buying for a loaded SUV or van	Load rating and inflation spec	Temperature grade
Choosing between touring tires	Correct fitment	Treadwear, traction, and date code
Checking a used car	Matching tire sizes across the axle	Age and UTQG marks
Shopping in winter regions	Season type and fitment	UTQG only after the tire type fits the weather

What To Match Before You Buy Replacement Tires

Start at the driver-door placard, not the old tire. The placard and the owner’s manual tell you the factory size and inflation spec for your vehicle. That matters because the tire already on the car may be wrong. People swap wheels, buy used cars with mixed tires, or fit a cheap replacement that only “sort of” matches. The placard cuts through that guesswork.

Next, match the tire type to the job. All-season, summer, winter, highway-terrain, and all-terrain tires can share a size yet behave in wildly different ways. A taller tread block may hum more. A winter tire may skip a UTQG grade. A summer tire may grip hard in warm weather and feel poor once the temperature drops. Read the ratings after you pick the right category.

Then keep sets consistent across each axle. Mixing different load indexes, speed symbols, or tire types on the same axle can make the car feel odd under braking or in a wet turn. If you must replace one tire, check the remaining tread depth too. A fresh tire paired with a worn mate can create its own set of issues.

Mistakes That Trip People Up

These are the slipups that cause most of the confusion in a tire shop:

• Reading only the size. A tire can match the wheel diameter yet miss the needed load index or speed symbol.
• Treating treadwear like a lifespan promise. It’s a comparison grade, not a contract.
• Assuming traction grades rank all grip. They rate wet straight-line braking, not every kind of grip.
• Ignoring the date code. Age matters when two “new” tires have been stored for different lengths of time.
• Mixing tire categories. Same size does not mean same behavior.
• Using sidewall max pressure as the everyday setting. Your vehicle placard is the place to start for normal inflation.

The Sidewall Stops Feeling Cryptic Once You Know The Order

If you read a tire left to right, the code starts to make sense fast. Size tells you if it fits. Load index and speed symbol tell you what the tire can carry and the speed category it was built around. UTQG grades give you a federal comparison for wear, wet braking, and heat on many passenger tires. The DOT code tells you when that tire was made. Put those pieces together, and “How are tires rated?” turns from a vague shop question into a clean, useful check you can do in under a minute.