How to Read Tire Sidewalls Before You Buy

A tire can look fine from across the parking lot and still be the wrong fit for your vehicle. The numbers and letters molded into the rubber tell you its size, age, weight capacity, speed capability, and whether it is built for all-season, winter, or specialty use. Knowing how to read tire sidewalls helps you order the right tire the first time, avoid a costly mismatch, and keep your vehicle driving the way it should.

Start by looking at the sidewall of the tire currently on your vehicle. You will find a string similar to P215/60R16 95H. That one line carries most of the information you need when pricing tires.

How to Read Tire Sidewalls: Start With Tire Size

Using P215/60R16 95H as the example, the first letter is the tire type. The P means passenger vehicle tire. You may also see LT for light truck, commonly used on pickups, vans, and SUVs that carry heavier loads. A tire with no letter may use a European metric designation. It can still fit certain vehicles, but do not assume it is interchangeable without checking the manufacturer requirements.

The next number, 215, is the tire width in millimeters. This tire is about 215 millimeters wide from sidewall to sidewall. Wider is not automatically better. A wider tire can change steering feel, clearance, fuel economy, road noise, and how the tire performs in rain or snow.

After the slash, 60 is the aspect ratio. This number tells you the sidewall height as a percentage of the tire width. In this case, the sidewall height is 60 percent of 215 millimeters. A lower number, such as 45 or 50, means a shorter sidewall and usually a firmer, more responsive feel. A higher number provides more sidewall cushion, which can be useful on rough roads and for everyday driving.

The R means radial construction. Almost every modern passenger tire is radial. You may occasionally see a D for diagonal or bias-ply construction, especially on certain trailers, agricultural equipment, or specialty applications. The construction type matters, so match what your vehicle or equipment calls for.

The final number in the main size, 16, is the wheel diameter in inches. This tire fits a 16-inch wheel. It does not mean the tire itself is 16 inches tall. Never try to mount a tire on a wheel with a different diameter, even if the numbers are close.

Load Index and Speed Rating Matter Too

The 95H at the end of the example is not extra information to ignore. The number 95 is the load index, which identifies the maximum load the tire can support when properly inflated. A 95 load index equals 1,521 pounds per tire. Four tires do not always carry weight evenly, but the rating gives the capacity the vehicle needs.

The letter H is the speed rating. An H-rated tire is approved for sustained speeds up to 130 mph under controlled conditions. That does not mean it is a recommendation to drive at that speed. It is a performance and heat-management rating.

Common ratings include S, T, H, V, W, and Y. Higher letters generally indicate greater speed capability, but they can also affect ride quality, tread life, and price. A high-performance tire may feel sharper in corners but wear faster than a touring tire. For most drivers, the right choice is to meet or exceed the vehicle manufacturer’s required load index and speed rating.

You may also see XL, meaning Extra Load, or SL, meaning Standard Load. XL tires are designed to carry more weight at higher inflation pressure. They are common on heavier SUVs, crossovers, trucks, and some electric vehicles. Do not switch between SL and XL simply because the physical size matches. Check the door-jamb tire placard and your owner’s manual first.

Find the DOT Code Before Buying Used Tires

Every tire sold for road use in the United States has a DOT code. Look for the letters DOT followed by a series of letters and numbers. The last four digits show when the tire was made.

For example, a tire ending in 2325 was manufactured in the 23rd week of 2025. This is one of the most useful numbers to check when inspecting used tires, a spare tire, or tires that have been sitting in a garage.

Age matters because rubber hardens and breaks down over time, even when tread depth still looks good. Sun exposure, heat, storage conditions, low use, and improper inflation can all speed up that process. There is no one age limit that applies to every tire, but an older tire deserves a close inspection for cracking, bulges, vibration, and uneven wear. If a used tire has a tempting price but an old DOT date, it may not be the value it appears to be.

Understand Traction, Temperature, and Treadwear Grades

Many passenger tires display UTQG ratings on the sidewall. UTQG stands for Uniform Tire Quality Grading and includes treadwear, traction, and temperature.

A treadwear number such as 500 gives a comparison rating for expected tread life under standardized testing. In simple terms, a 500-rated tire should last longer than a 300-rated tire when tested under the same conditions. Real-world tread life still depends on alignment, tire pressure, vehicle weight, driving habits, and road conditions. A higher treadwear number is helpful, but it is not a mileage guarantee.

Traction grades are AA, A, B, and C. They measure straight-line wet braking traction on specific test surfaces. AA is the highest grade. This grade does not tell the full story about cornering grip, hydroplaning resistance, or snow performance, but it is worth comparing when choosing between similar tires.

Temperature grades are A, B, and C. They indicate a tire’s ability to resist heat buildup at speed. Grade A is the highest. Heat is one reason proper inflation and correct load rating matter so much. An underinflated tire flexes more, creates more heat, and can fail sooner.

Look for All-Season and Winter Markings

The M+S marking means Mud and Snow. It is common on all-season tires and indicates the tread design meets a basic industry standard for light snow traction. It does not mean the tire performs like a dedicated winter tire on ice, packed snow, or below-freezing roads.

For real winter capability, look for the Three-Peak Mountain Snowflake symbol. This marking means the tire meets a more demanding snow-traction test. It appears on dedicated winter tires and some all-weather tires. For Niagara winters, the best choice depends on how much you drive, where you travel, whether you deal with unplowed roads, and how much cold-weather traction matters to you.

All-weather tires can be a practical middle ground for drivers who want year-round use with stronger winter performance than a typical all-season tire. Dedicated winter tires usually provide better cold-weather grip, but they require a seasonal changeover and a second set of tires or wheels.

Other Sidewall Markings You May See

Some markings are specific to the tire’s construction or approved use. Tubeless means the tire does not require an inner tube. Radial confirms radial construction. Outside and Inside appear on asymmetrical tires and must face the correct direction when mounted. Directional tires may show an arrow labeled Rotation, which must point forward when the vehicle moves ahead.

You may also see Run Flat, RF, or a manufacturer-specific run-flat designation. These tires can sometimes be driven for a limited distance after losing air pressure, but only under the tire maker’s stated conditions. They are not all interchangeable with conventional tires, and the vehicle may need a tire-pressure monitoring system designed for them.

A maximum pressure number is another commonly misunderstood marking. If the sidewall says “Max Press 51 PSI,” that is the maximum cold inflation pressure for the tire, not the pressure you should automatically use. Your correct everyday pressure is normally on the vehicle’s tire placard, usually inside the driver’s door jamb. Check pressures when the tires are cold.

Match the Tire to the Vehicle, Not Just the Numbers

The original tire size is usually the safest place to start, but there are times when an alternate size makes sense. A truck owner may need a heavier load range. A driver may choose winter tires on a smaller wheel for more sidewall and lower replacement cost. A performance vehicle may use staggered sizes, with different tires front and rear.

Those changes need to be planned correctly. Tire diameter affects speedometer accuracy, gearing, clearance, and electronic safety systems. Mixing brands, tread patterns, or significantly different tread depths can also create issues, especially on all-wheel-drive vehicles. If you are replacing just one tire, make sure the new tire is compatible with the remaining tires and your vehicle’s drivetrain requirements.

Bring in the tire size from your sidewall or the information from your door-jamb placard before you buy. If you are unsure which rating, tread type, or winter option fits your driving, Auto Know Car Parts can help you price out the right tires for your vehicle and get you moving without wasting money on the wrong set. A clear photo of the sidewall is often enough to start the conversation.