Reading Your Tire Sidewall: A Quick Reference for Everyday Drivers

What That String of Numbers and Letters Actually Means

Flip to the side of any tire and you'll find a stamped sequence that looks something like P215/65R16 98H. It's not random — every character describes a specific physical or performance attribute of that tire. Once you know the pattern, you can read any passenger tire in under a minute.

Here's how to break down the code, character by character:

• Letter prefix (P, LT, ST): The service type. P stands for passenger vehicle, LT for light truck, and ST for special trailer. Some European-style tires skip this prefix entirely.
• Three-digit number (e.g., 215): Section width — how wide the tire is from sidewall to sidewall, measured in millimeters.
• Two-digit number after the slash (e.g., 65): Aspect ratio — the tire's sidewall height expressed as a percentage of its section width. A lower number means a shorter, sportier sidewall.
• Construction letter (R, D, B): Almost always R for radial, which is standard on modern vehicles. D (diagonal/bias-ply) appears on older vehicles and some trailers.
• Two-digit rim diameter (e.g., 16): The wheel size this tire fits, measured in inches.
• Load index (e.g., 98): A number that corresponds to the maximum weight each tire can safely support. A load index of 98 equals roughly 1,653 lbs per tire.
• Speed rating (e.g., H): The maximum sustained speed the tire is designed to handle. H = up to 130 mph; V = up to 149 mph; T = up to 118 mph.

Always replace tires with ones that match or exceed the load index and speed rating specified in your owner's manual or on the driver's door jamb sticker — never go lower.

Other Markings Worth Knowing

Beyond the main size code, tire sidewalls carry several other stamped markings that provide safety and manufacturing data.

DOT Code and Manufacturing Date

Look for a string beginning with DOT followed by a series of characters. The last four digits are the most useful: they indicate the week and year the tire was manufactured. For example, 2319 means the 23rd week of 2019. Most tire manufacturers and safety experts consider tires older than six years to be candidates for inspection regardless of tread depth, and tires beyond ten years should typically be replaced — even if they look fine on the surface.

UTQG Ratings

The Uniform Tire Quality Grading (UTQG) system, required by the U.S. Department of Transportation, gives you three standardized scores:

• Treadwear: A comparative index. A tire rated 400 should last roughly twice as long as one rated 200 under the same test conditions.
• Traction: Rated AA, A, B, or C — reflects wet stopping performance. AA is the highest.
• Temperature: Rated A, B, or C — indicates how well the tire dissipates heat at sustained speeds. A is the highest.

UTQG grades are measured under controlled government test conditions, so treat them as comparative guides rather than absolute guarantees of real-world performance.

M+S and the Three-Peak Mountain Snowflake

An M+S (mud and snow) stamp indicates basic all-season capability. The Three-Peak Mountain Snowflake (3PMSF) symbol — a snowflake inside a mountain outline — is a stricter certification indicating the tire meets specific snow traction standards. If you drive in regions with serious winter weather, look for the 3PMSF symbol rather than relying on M+S alone.

Understanding your tire's sidewall makes it easier to shop for replacements confidently and to spot mismatches before they become problems. Pair this knowledge with routine checks — see our guide on why tire pressure matters more than most drivers realize — and you'll stay ahead of most common tire issues. For related dashboard alerts, decoding your car's warning lights is a useful companion read.