That string of letters and numbers on your tire’s sidewall — something like P215/60R16 94H — looks like a secret code, but every character carries useful information about size, capacity, and age. Knowing how to read tire sidewall markings helps you buy the correct replacement tires, decode how old your tires are, and understand what your tires can safely handle.
Let us decode each marking step by step, using P215/60R16 94H as our example.
How to Read Tire Sidewall Size: P215/60R16 Explained
The size code has four parts before the wheel diameter:
- P — Service type. P means passenger vehicle. LT means light truck (stronger construction for heavier loads). ST means special trailer — never put ST tires on a passenger car. If there is no letter, it is a European “metric” size, functionally similar to P.
- 215 — Section width in millimeters. This is the tire’s width from sidewall to sidewall at its widest point: 215 mm, or about 8.5 inches. Wider is not automatically better — it must match your wheels and vehicle spec.
- 60 — Aspect ratio. The sidewall height as a percentage of the section width. Here, the sidewall is 60 percent of 215 mm, or about 129 mm tall. Lower numbers (like 45 or 40) mean shorter, sportier sidewalls; higher numbers (65, 70) mean taller, more comfort-oriented sidewalls.
- R — Construction type. R means radial, which is virtually every modern tire. (You may still see D for diagonal bias-ply on some trailer tires.)
- 16 — Wheel diameter in inches. This tire fits a 16-inch wheel. This number must match your wheels exactly — there is no fudging it.
Critical rule: when replacing tires, match the full size code unless you are doing a deliberate “plus sizing” change with professional guidance. The wrong overall diameter throws off your speedometer, odometer, gearing, and ABS calibration.
Load Index and Speed Rating: 94H
After the size come two characters that describe capability:
Load Index (94)
The load index is a numeric code for how much weight each tire can carry. Higher is stronger:
- 94 = 1,477 lbs (670 kg) per tire. Multiply by four tires for total capacity — but never exceed your vehicle’s GVWR on the door placard.
- Common passenger indexes: 91 (1,356 lbs), 94 (1,477 lbs), 98 (1,653 lbs).
- Light truck tires use higher indexes, often 115+ (2,679 lbs).
Never install tires with a lower load index than your vehicle requires. Going higher is fine.
Speed Rating (H)
The letter is the maximum sustained speed the tire is certified for:
- S: 112 mph | T: 118 mph | H: 130 mph | V: 149 mph | W: 168 mph | Y: 186 mph
You do not need a Y-rated tire for a family sedan, but never downgrade below the manufacturer’s specified rating — the rating also correlates with handling response and heat tolerance.
DOT Code: How Old Are Your Tires?
Every tire sold in the U.S. carries a DOT code. The last four digits are the birth date: the first two are the week, the last two are the year. For example, DOT XXXX 3223 means the tire was made in the 32nd week of 2023.
This matters because tires age out. Most manufacturers recommend replacing tires at 6 to 10 years from the manufacture date regardless of tread depth — rubber compounds harden and crack with age. A tire with perfect tread from 2016 is not safe in 2026. If you only see three digits at the end, the tire was made before 2000 — replace it immediately.
UTQG Ratings: Treadwear, Traction, Temperature
The Uniform Tire Quality Grading stamp shows three ratings, e.g., 500 A A:
- Treadwear (500): A relative number — higher means longer-wearing. A 500-rated tire should last roughly twice as long as a 250-rated one from the same manufacturer. Do not compare treadwear numbers across brands; testing is self-reported.
- Traction (A): Graded AA, A, B, or C for wet straight-line grip. A or AA is what you want.
- Temperature (A): Graded A, B, or C for heat resistance at speed. A is best.
Other Markings Worth Knowing
- M+S (Mud and Snow): An all-season tread designation. It is a tread-pattern claim, not a tested winter rating.
- Three-Peak Mountain Snowflake (3PMSF): The tire passed actual snow-traction testing — a genuine winter-capable rating. Look for this if you drive in real winter conditions.
- XL (Extra Load): Reinforced construction for heavier loads at higher pressures. If your placard calls for XL, do not substitute standard-load tires.
- Rotation arrow: On directional tires, an arrow shows the required rolling direction — critical when mounting and rotating.
- “Outside”: On asymmetric tires, this side must face outward.
- Max pressure and max load: Molded limits for the tire itself — remember, your car’s placard spec is what you inflate to daily.
- Treadwear indicators: Small raised bars in the tread grooves at 2/32 inch — when tread wears flush with them, the tire is legally worn out.
Quick-Reference: Decoding Any Sidewall in 30 Seconds
- Read the size (e.g., P215/60R16) — width, aspect ratio, wheel diameter.
- Check load index and speed rating (e.g., 94H) — capacity and speed capability.
- Find the DOT date (last 4 digits) — if over 6 years old, plan replacement.
- Note UTQG, M+S or snowflake, XL, and directional arrows.
Common Sidewall Mistakes
- Buying by diameter alone. A “16-inch tire” is not one size — 205/55R16 and 225/60R16 are very different tires.
- Ignoring the load index when chasing a bargain — an under-rated tire is a safety compromise.
- Mixing speed ratings or sizes across axles, which confuses ABS and stability control.
- Judging age by tread. Always check the DOT date — old rubber with deep tread is still old rubber.
- Mounting directional tires backward after rotation, killing their wet-weather performance.
Once you can read the sidewall, you can verify any tire quote in seconds, spot an aged-out spare before you need it, and never again wonder what that alphabet soup means.