How to Read a Tire Sidewall: What Every Number & Letter Means

Every tire on your car has a wall of numbers, letters, and symbols molded into the rubber. Most drivers ignore them completely — but knowing how to read a tire sidewall can tell you the tire’s size, how much weight it can carry, how fast it can safely go, how old it is, and whether it’s the right tire for your car. None of it is complicated once someone explains what you’re looking at.

What You Need to Know Before You Start

All of the important information on a tire is molded directly into the sidewall. The flat rubber section on the side of the tire between the tread and the wheel rim. You don’t need any tools to read it. You just need to know what each section means and where to find it.

The information is organized in a specific order, and once you learn the sequence it takes about 30 seconds to read a tire completely. The most important section is the tire size code, a combination of letters and numbers that looks something like this:

P215/65R15 95H

That one string of characters tells you almost everything you need to know about the tire. Here’s what each part means.

The Short Answer: Here’s What the Code Means

Using P215/65R15 95H as the example:

P = Tire type (Passenger)
215 = Tire width in millimeters
65 = Aspect ratio (sidewall height as a percentage of width)
R = Construction type (Radial)
15 = Wheel diameter in inches
95 = Load index (maximum weight the tire can carry)
H = Speed rating (maximum safe sustained speed)

Why Reading Your Tire Sidewall Matters

Most drivers only think about their tires when something goes wrong. But the sidewall tells you things that affect your safety every single time you drive. Whether your tires are the right size for your car, whether they can handle the weight of your vehicle and everything in it, how fast they can safely go, and whether they’re too old to trust even if the tread looks fine. Buying the wrong replacement tire because you didn’t read the sidewall is a surprisingly common mistake that can affect your car’s handling, fuel economy, and safety.

Breaking Down Every Part of the Tire Sidewall

The Tire Type Letter

The first letter or letters in the size code tell you what type of vehicle the tire is designed for.

P stands for Passenger. These are the most common tires and are designed for cars, SUVs, crossovers, minivans, and smaller pickup trucks.

LT stands for Light Truck. These tires are built for heavier-duty use — vehicles that carry heavy loads, tow trailers, or need extra durability. Three-quarter ton and one-ton trucks and heavy-duty SUVs typically use LT tires.

ST stands for Special Trailer. These tires are designed for trailers only — fifth wheels, boat trailers, utility trailers. Never put ST tires on a passenger vehicle or truck.

T stands for Temporary. This is the designation for small spare tires — the compact “donut” spare in your trunk. Temporary spares are not designed for highway speeds or long distances.

If there is no letter before the first number, the tire is a Euro-metric tire — a European sizing standard. These tires are physically similar to P-metric tires but may have a different load capacity at the same size.

The Three-Digit Width Number

The three-digit number immediately following the type letter is the tire’s section width in millimeters. This is the distance from the widest point of one sidewall to the widest point of the other sidewall when the tire is properly mounted and inflated.

In the example P215/65R15, the tire is 215 millimeters wide — about 8.5 inches. A wider tire covers more road surface, which generally improves grip and handling. A narrower tire can improve fuel economy and perform better in snow by cutting through to the road surface instead of floating on top.

The Aspect Ratio

The two-digit number after the slash is the aspect ratio. This tells you the height of the tire’s sidewall as a percentage of the tire’s width.

In P215/65R15, the aspect ratio is 65. That means the sidewall height is 65% of 215mm — approximately 140mm or about 5.5 inches tall.

Lower aspect ratios mean shorter, stiffer sidewalls. Tires with aspect ratios of 55 or below are considered low-profile tires. They look sleek, provide sharper handling and steering response, but give a stiffer ride and are more vulnerable to pothole damage. Higher aspect ratios mean taller sidewalls, a softer ride, and more cushioning over rough roads.

This number matters when replacing tires. If you change the aspect ratio without adjusting the wheel diameter, your speedometer will read incorrectly and your car’s handling will change.

The Construction Letter

The letter after the aspect ratio tells you how the tire is built internally.

R stands for Radial construction. This is the industry standard for virtually every passenger tire sold today. In a radial tire, the internal cords run perpendicular to the direction of travel, which provides better fuel economy, grip, ride comfort, and durability than older designs.

D stands for Diagonal or Bias-ply construction. The cords crisscross at an angle. Bias-ply tires are now mostly used on certain trailers, motorcycles, and vintage vehicles.

B stands for Belted Bias construction — a hybrid design that’s rarely seen on modern passenger vehicles.

Almost every tire you’ll encounter on a regular car or truck will have an R.

The Wheel Diameter

The number after the construction letter is the wheel diameter in inches. This tells you what size wheel the tire is designed to fit.

In P215/65R15, the tire fits a 15-inch wheel. This number must match your wheel exactly — a tire designed for a 17-inch wheel cannot be mounted on a 16-inch wheel. When buying replacement tires, this is one of the most important numbers to get right.

The Load Index

After the tire size code, you’ll see a two or three-digit number — this is the load index. It represents the maximum weight each individual tire can safely carry when inflated to its maximum pressure.

The load index is not a weight in pounds — it’s a code number that corresponds to a weight on a standardized chart. Here are the most common load index numbers for passenger vehicles:

85 = 1,135 lbs per tire
88 = 1,235 lbs per tire
91 = 1,356 lbs per tire
94 = 1,477 lbs per tire
97 = 1,609 lbs per tire
100 = 1,764 lbs per tire
104 = 1,984 lbs per tire
107 = 2,149 lbs per tire

To find your vehicle’s total load capacity, multiply the load index weight by four. Four tires with a load index of 94 (1,477 lbs each) give you a total capacity of 5,908 lbs.

Never install tires with a lower load index than the original tires on your vehicle. Going higher is fine — a higher load index provides an extra safety margin. Going lower puts you at risk of tire failure, especially when the car is fully loaded.

Passenger car tires typically have load indexes between 75 and 105. Light truck tires sometimes show two numbers separated by a slash — for example, 108/104. The first number is the single-tire rating, and the second is the rating when used in a dual rear wheel configuration.

The Speed Rating

The letter at the very end of the size code is the speed rating. It tells you the maximum sustained speed the tire is certified to handle safely under its maximum load.

The most common speed ratings you’ll see on everyday vehicles:

S = 112 mph — common on family sedans and light trucks
T = 118 mph — common on minivans and family sedans
H = 130 mph — common on sport sedans and coupes
V = 149 mph — common on performance vehicles
W = 168 mph — high-performance sports cars
Y = 186 mph — exotic and ultra-high-performance vehicles
Z = Over 149 mph — appears in the size code on some high-performance tires

One quirk worth knowing: the letter H is out of alphabetical order. It falls between U and V on the speed rating scale rather than after G. This is a historical artifact — H originally stood for “high performance” and has kept its place in the rating system ever since.

The speed rating is not a suggestion for how fast to drive. It’s the maximum the tire is engineered to handle. Always match or exceed your vehicle manufacturer’s recommended speed rating when replacing tires. Never go below it.

A tire that has been punctured and repaired, even properly, has a maximum safe speed of 85 mph regardless of its original speed rating.

Other Markings on the Sidewall

The DOT Code and Manufacture Date

Every tire sold in the United States has a DOT (Department of Transportation) code molded into the sidewall. It starts with the letters DOT and is followed by up to 12 characters. The most important part for drivers is the last four digits. These tell you exactly when the tire was made.

The first two of the last four digits are the week of manufacture (01 through 52). The last two digits are the year.

So a tire with a DOT code ending in 2322 was made in the 23rd week of 2022.

This matters because tires age even if you don’t drive on them. Rubber breaks down over time from heat, UV exposure, and oxidation. A process that happens whether the tire is on your car or sitting in a warehouse. A tire can look perfectly fine on the outside while being structurally compromised on the inside.

NHTSA and most major tire manufacturers including Michelin, Goodyear, Bridgestone, and Continental recommend having tires inspected at every service visit once they are 6 years old. After 10 years from the manufacture date, tires should be replaced regardless of how much tread is left or how they look. This applies to spare tires too — the spare sitting in your trunk ages just like the tires on your wheels.

If you buy a used car, check the DOT codes on all four tires before you drive it home.

UTQG Ratings — Treadwear, Traction, and Temperature

Most tires sold in the United States have three additional ratings molded into the sidewall as part of the Uniform Tire Quality Grading system established by NHTSA. They look like this: TREADWEAR 400 TRACTION A TEMPERATURE B

Treadwear is a comparative number. A tire rated 400 is expected to last twice as long as a tire rated 200 under controlled test conditions. These numbers are set by each tire manufacturer using a government-prescribed test course, which means they’re useful for comparing tires within a brand’s lineup but less reliable for comparing across different brands.

Traction is rated AA, A, B, or C — measuring the tire’s ability to stop on wet pavement in a straight line. AA is the best. Any rating below C is considered unacceptable for road use, though you’ll almost never see those ratings on tires sold for passenger vehicles.

Temperature is rated A, B, or C — measuring the tire’s ability to dissipate heat at high speeds. A is the best. Again, C is the minimum acceptable for road use.

MAX LOAD and MAX PRESS

You’ll see two numbers labeled MAX LOAD and MAX PRESS (or MAX PSI) somewhere on the sidewall. These are the maximum load the tire can carry and the maximum air pressure it can hold.

These are not the numbers to use when inflating your tires. The correct tire pressure for your vehicle is on the sticker inside your driver’s door jamb or in your owner’s manual. The MAX PRESS on the tire sidewall is the upper limit the tire can physically handle — not the recommended operating pressure.

M+S and the Mountain Snowflake Symbol

If you see M+S on your tire, it indicates the tire is rated for mud and snow conditions based on the manufacturer’s own criteria. This is a self-certified designation and does not require standardized performance testing.

The Three-Peak Mountain Snowflake symbol (3PMSF) — which looks like a snowflake inside a mountain outline — is a higher standard. Tires carrying this symbol have passed standardized government tests for winter traction performance and are certified for use in regulated winter driving conditions. If you live somewhere with real winters, look for the mountain snowflake symbol rather than just M+S when buying tires.

RADIAL

Tires with radial construction are required to display the word RADIAL on the sidewall. This confirms the internal construction type and matches the R in the size code.

TUBELESS or TUBE TYPE

Most modern tires are tubeless — they seal directly to the wheel rim without requiring an inner tube. If a tire says TUBELESS, that’s what you have. TUBE TYPE means an inner tube is required, which is now rare on passenger vehicles.

How to Use the Sidewall When Buying Replacement Tires

When you need new tires, find the size code on your current tires and match it exactly — same width, same aspect ratio, same wheel diameter, same or higher load index, same or higher speed rating. The easiest place to find your vehicle’s recommended tire size is on the sticker inside your driver’s door jamb or in your owner’s manual. Those sources are more reliable than reading a worn sidewall if your current tires have ever been changed from the original size.

Never mix tire types on the same axle. If you’re only replacing two tires, put the new ones on the rear axle regardless of whether your car is front-wheel drive, rear-wheel drive, or all-wheel drive. New tires on the rear reduces the risk of losing control in wet conditions.

Check the DOT date code when buying new tires — even from a reputable shop. Tires can sit in warehouses for a year or more before being sold. A tire bought new in 2026 with a manufacture date of 2023 already has three years of age on it.

How to Figure Out What You’re Looking At

You found a used car you’re thinking about buying and want to check the tire age → Look at the last four digits of the DOT code on each tire. First two digits are the week, last two are the year. If any tire is over 6 years old, factor a new set into your budget.

You’re buying replacement tires and aren’t sure what size you need → Check the sticker inside your driver’s door jamb first. If it’s not there, read the size code off your current tires — it’s the longest string of characters on the sidewall.

You want to know if your tires are good enough for winter → Look for the Three-Peak Mountain Snowflake symbol. M+S alone doesn’t guarantee winter performance.

Your car feels like it’s handling differently after getting new tires → Check whether the new tires match the original aspect ratio and width. A change in either will affect how the car feels and can affect speedometer accuracy.

You see XL or Extra Load on the sidewall → This means the tire can carry more weight than a standard load tire of the same size when inflated to a higher pressure. Some vehicles require XL tires — check your owner’s manual.

Tips for Keeping Track of Your Tire Information

Take a photo of the full size code on one of your tires and keep it in your phone. When it’s time to buy replacements, you’ll have the exact size without having to crawl around in a parking lot.

Check the DOT date on all four tires once a year. Takes 30 seconds per tire and can tell you whether replacement is coming up before you get a blowout as a warning.

Write down your tire size when you buy new tires. Tire shops sometimes install a slightly different size than what was originally on the car — this is usually fine, but you want to know what’s actually on your vehicle.

If you see XL or Reinforced on a tire, make sure any replacement tires also carry that designation. XL tires are inflated to a higher pressure and removing that designation can affect your car’s load capacity and handling.

The sidewall of your tire is a complete reference guide to everything about that tire. The size code tells you the width, sidewall height, construction type, and wheel size. The load index tells you how much weight the tire can carry. The speed rating tells you its maximum safe speed. The DOT code tells you how old it is. The UTQG ratings give you a rough comparison of tread life, wet traction, and heat resistance.

You don’t need to memorize all of it. But knowing where to find your tire size when you need new ones, and knowing how to check the manufacture date to catch aging tires before they fail, are two things that genuinely affect your safety on the road.

How to Check Car Tire Pressure and Add Air Safely
Why Is My Tire Pressure Light Still On After Adding Air?
How to Change a Flat Tire
How to Check Your Brake Fluid
Winter Tires vs All-Season vs Summer Tires
How to Put Air in Tires
Why Does My Car Shake at Idle But Smooth While Driving
How to Read Dashboard Warning Lights

FAQs

What does P mean on a tire?
P stands for Passenger. It means the tire is designed for passenger vehicles — cars, SUVs, crossovers, minivans, and smaller trucks. LT means Light Truck, designed for heavier-duty use.

What do the three numbers on a tire mean?
The first three-digit number is the tire’s width in millimeters. The two digits after the slash are the aspect ratio — the sidewall height as a percentage of the width. The two-digit number at the end of the size code is the wheel diameter in inches.

How do I find out how old my tires are?
Look for the DOT code on the sidewall — it starts with the letters DOT. The last four digits are the manufacture date. The first two digits are the week, the last two are the year. A code ending in 1824 means the tire was made in the 18th week of 2024.

How old is too old for tires?
NHTSA and major tire manufacturers including Michelin, Goodyear, and Bridgestone recommend having tires inspected at every service visit after 6 years. Tires should be replaced by 10 years from the manufacture date regardless of how much tread remains or how they look.

What does the H or V mean at the end of a tire size?
That’s the speed rating — the maximum sustained speed the tire is certified to handle safely. H means 130 mph. V means 149 mph. T means 118 mph. Always match or exceed your vehicle manufacturer’s recommended speed rating.

What is the load index on a tire?
The load index is the two or three-digit number before the speed rating letter. It corresponds to the maximum weight each tire can carry when properly inflated. Load index 94 means each tire can carry 1,477 lbs. Multiply by four for your total vehicle load capacity.

What does XL mean on a tire?
XL stands for Extra Load. It means the tire can carry more weight than a standard load tire of the same size when inflated to a higher pressure. Some vehicles require XL tires — check your owner’s manual and match that designation when buying replacements.

What does M+S mean on a tire?
M+S stands for Mud and Snow. It means the tire has been rated by the manufacturer for mud and light snow conditions. It does not require standardized performance testing. For verified winter performance, look for the Three-Peak Mountain Snowflake symbol instead.

Can I put a different size tire on my car?
You should match the original size as closely as possible. Changing the width, aspect ratio, or wheel diameter affects your speedometer accuracy, handling, and load capacity. Always consult your owner’s manual or door jamb sticker for the correct size.

What does the DOT number on a tire mean?
DOT stands for Department of Transportation. The DOT code certifies that the tire meets U.S. safety standards. The last four digits of the DOT code are the manufacture date — the first two are the week of the year, the last two are the year.

What is UTQG on a tire?
UTQG stands for Uniform Tire Quality Grading — a rating system developed by the U.S. government. It grades tires on treadwear (a comparative number), traction (AA, A, B, or C for wet stopping ability), and temperature (A, B, or C for heat resistance).

Should I check the DOT date when buying new tires?
Yes. Tires can sit in warehouses or on shop shelves for a year or more before being sold. A tire purchased new can already be 1-2 years old by its manufacture date. Checking the DOT code when buying new tires ensures you’re not starting with aged rubber.

About The Author

Dmitri is an automotive professional with experience in vehicle operations, financing, and ownership education. He writes practical, easy-to-follow guides to help drivers make informed decisions about car maintenance and comfort features.

How to Read a Tire Sidewall — What All Those Numbers and Letters Actually Mean