How to Read a Tire Sidewall and Decode Every Number

Your tire's sidewall is covered in codes that tell you its exact size, how much weight it can carry, how fast it is rated, when it was built, and how long the tread should last. Once you can read P215/65R15 95H and the DOT date, buying the right replacement becomes simple and safe. Here is the full decode.

The main tire size code, decoded

The headline marking looks like P215/65R15 95H. Each part means something specific, and getting any of them wrong can affect your speedometer, your handling, and even rubbing against the bodywork.

• P is the type. P means P-metric (passenger car). LT means light truck, and no letter means Euro-metric, which is largely interchangeable with P-metric.
• 215 is the section width in millimeters, measured across the widest part of the tire.
• 65 is the aspect ratio: the sidewall height is 65 percent of the width. A lower number means a shorter, sportier sidewall.
• R is the construction. R means radial, the standard for virtually all modern cars. D would mean bias-ply.
• 15 is the wheel diameter in inches the tire is designed to mount on.
• 95 is the load index, a coded maximum weight per tire.
• H is the speed rating, a coded maximum sustained speed.

Load index: how much weight the tire carries

The load index is a number that maps to a maximum weight in a standardized chart. A load index of 95, for example, corresponds to about 1,521 pounds per tire. The figure is not pounds directly, so you read it off a load-index table printed by tire makers like Goodyear or Continental. Never fit a tire with a lower load index than your vehicle's original specification, because that reduces the safe carrying capacity and can overheat under load.

Speed rating: the letter at the end

The trailing letter is the speed rating, the maximum sustained speed the tire was tested for. Common ratings are T (118 mph), H (130 mph), V (149 mph), and W (168 mph). It is not an invitation to drive that fast; it reflects the tire's heat tolerance and construction quality. Matching or exceeding the original rating keeps the handling and safety margin the manufacturer intended.

The DOT date code: how old is the tire?

Tires age even when unused, and rubber dries out over time. The DOT code on the sidewall ends in a four-digit date: the first two digits are the week of manufacture and the last two are the year. A code ending 4823 means the tire was built in the 48th week of 2023. NHTSA and most automakers advise replacing tires that are six to ten years old regardless of tread, and inspecting any tire over six years old closely. Always check the date when buying so-called new tires, since they may have sat in a warehouse for years.

UTQG: treadwear, traction, and temperature

The Uniform Tire Quality Grading marks help compare tires. Treadwear is a relative number, like 400 or 500, where higher generally means longer-lasting tread, though it is only comparable within one manufacturer's lineup. Traction grades wet-stopping ability from AA (best) down to C. Temperature grades heat resistance from A to C. These grades are molded into the sidewall and required on passenger tires sold in the United States. They help, but real-world reviews and the tire's intended use matter just as much.

Maximum load and pressure markings

Below the main size code you will find two more useful numbers spelled out in words. The maximum load tells you the most weight that single tire can safely carry, stated in pounds and kilograms, and it corresponds to the coded load index. The maximum pressure is the highest cold inflation pressure the tire is built to hold. This is the number people mistakenly inflate to; it is a ceiling, not a target. Your actual cold pressure should always come from the vehicle's door-jamb placard, which our guide on checking tire pressure explains in full. Reading the max-load and max-pressure lines simply confirms the tire is rated for your car, not how much air to put in.

Treadwear indicators and the wear bars

Look closely between the tread blocks and you will find small raised bars running across the grooves. These are the tread-wear indicators, molded to a height of 2/32 of an inch, the legal minimum tread depth in most U.S. states. When the surrounding tread wears down level with these bars, the tire is legally and practically worn out and must be replaced. The letters TWI or a small triangle on the shoulder mark where to look. They are a built-in, no-tools reminder, though a tread-depth gauge gives you earlier warning so you can budget for replacement rather than being caught out.

Other markings you may see

Several extra codes appear on many tires and are worth recognizing:

• M+S or the 3PMSF snowflake: winter and all-season capability, with the snowflake being the tested, meaningful winter rating.
• Rotation arrow: on directional tires, showing which way the tread must spin. It dictates how the tire may be rotated.
• Inside / Outside or Asymmetric: on asymmetric tires that must be mounted with a specific face outward.
• Tread, Sidewall, plies: a construction note listing the layers and materials, required by U.S. regulation.
• Country of manufacture and brand-specific codes: useful for warranty and recall lookups.
• Approval marks: letters such as MO, AO, or a star indicate a tire was tuned and approved for a specific automaker, and matching them preserves the original handling balance.

You do not need to memorize all of these, but recognizing them helps when you compare two tires that look identical in size yet differ in winter rating, mounting direction, or factory approval. Those differences change how the tire behaves and whether it suits your car.

Why getting the size right matters

Fitting a tire that differs from the original in diameter changes your effective gear ratio and throws off the speedometer and odometer, and on modern cars it can confuse ABS, traction control, and AWD systems that compare wheel speeds. A taller tire reads slower than you are going; a shorter one reads faster. It can also cause rubbing against the fender or suspension at full lock or over bumps. That is why matching the placard size, or staying within a percent or two of the original overall diameter when plus-sizing, is so important.

Putting it together when you buy

When you replace tires, match the size, load index, and speed rating to your door-jamb placard, not just to whatever was on the car, since a previous owner may have fitted the wrong size. If you want to experiment with a different size, use our tools and calculators to check that the new diameter stays close to the original so your speedometer reads correctly. Always buy tires in matching sets or at least matching axle pairs, and check the DOT date so you are not paying new-tire prices for old stock. Combine the sidewall date with tread depth, and you will know exactly when a tire is due, which our guide on when to replace tires covers in detail.

Frequently asked questions

What does P215/65R15 95H mean on my tire?

It is the full size code. P means passenger car, 215 is the section width in millimeters, and 65 is the aspect ratio, so the sidewall height is 65 percent of the width. R means radial construction, 15 is the wheel diameter in inches, 95 is the load index, and H is the speed rating, tested to 130 mph. Match all of these to your door placard.

How do I tell how old a tire is?

Read the DOT date code on the sidewall. It ends in four digits: the first two are the week of manufacture and the last two are the year. A code ending in 4823 means the 48th week of 2023. NHTSA and most automakers recommend replacing tires six to ten years old regardless of tread, because rubber dries out and cracks with age.

What is the load index and why does it matter?

The load index is a number that maps to a maximum weight per tire in a standardized chart, so 95 equals roughly 1,521 pounds. It is not pounds directly; you look it up on a load-index table. Never fit a replacement tire with a lower load index than the original specification, because it cuts the safe carrying capacity and can overheat under load.

What does the UTQG treadwear number tell me?

Treadwear is a relative durability grade molded into the sidewall, such as 400 or 500, where a higher number generally indicates longer-lasting tread. The catch is that it is only reliably comparable within a single manufacturer's own lineup, not across brands. Alongside it are traction grades from AA to C for wet braking and temperature grades from A to C for heat. Use them as one input among reviews.