Tire sizes · guide
How to read a tire sidewall
The size code, piece by piece
Using the Tire Industry Association’s example P225/60R16 97V (TIA):
| Part | Meaning | In this example |
|---|---|---|
| P | Tire type: P = passenger (P-metric), LT = light truck, ST = special trailer, T = temporary. No letter means Euro-metric, which can have different load capacities. | Passenger |
| 225 | Approximate section width, sidewall to sidewall, in millimeters | 225 mm |
| 60 | Aspect ratio: sidewall height as a percentage of the width | 60% of 225 mm ≈ 135 mm (TIA: approximately 135 mm) |
| R | Radial construction (B, X or – would mean bias-ply) | Radial |
| 16 | Rim (bead) diameter in inches | Fits a 16-inch wheel |
| 97V | Service description: load index + speed symbol | Load index 97, speed V |
Source: Tire Industry Association, Reading a Tire Sidewall.
Our tables use the size without the “P”, such as 225/65R17 or 235/55R19; each rim diameter has its own hub: 16-inch, 17-inch, 18-inch.
Load index and speed rating
- Load index is a code for the maximum weight one tire can carry when properly inflated. Michelin says a replacement’s load rating “must always meet or exceed the value specified by the vehicle manufacturer”; a higher load index is allowed but does not raise the vehicle’s own load limit. TIA adds: never install a lower load index than the original (Michelin, TIA).
- Speed symbol: Michelin lists H = 130 mph, V = 149 mph, W = 168 mph and Y = 186 mph as the maximum speed under proper inflation and load. TIA notes the symbol is “more like a performance rating” that reflects handling once installed.
- XL (Extra Load) tires have reinforced construction to carry more load at higher inflation than standard-load tires of the same size (Michelin).
- Where the correct size and ratings come from: the Tire and Loading Information Label on the driver’s door edge or post, or the owner’s manual (NHTSA).
The UTQG block
Most passenger tires also carry the three UTQG grades: TREADWEAR (a number), TRACTION (AA, A, B or C) and TEMPERATURE (A, B or C), as required by 49 CFR 575.104 (U.S. Code of Federal Regulations (eCFR)). They are explained in treadwear and traction and temperature.
The DOT code and date of manufacture
The letters “DOT” indicate the tire conforms to an applicable federal safety standard, and the Tire Identification Number (TIN) follows. Under 49 CFR 574.5 the TIN has 13 symbols for new tires: a three-symbol plant code, a six-symbol manufacturer’s code and a four-digit date code (49 CFR 574.5). The last four digits give the week and year. The regulation’s example is 0109 = “the first full calendar week of 2009”, the week beginning Sunday, January 4, 2009. NHTSA’s example: 0308 is the third week of 2008. The TIN might be on only one sidewall, so check both sides (NHTSA). Why age matters is covered in when to replace tires.
FAQ
What does 225/65R17 mean on a tire?
The tire is about 225 mm wide, its sidewall height is 65% of that width, it has radial construction, and it fits a 17-inch wheel. A load index and speed symbol usually follow.
Can I use a tire with a higher load index?
Michelin says a higher load rating is permitted but does not increase the vehicle’s maximum allowable load; never go lower than the vehicle manufacturer’s specification.
How do I find the date a tire was made?
Find the DOT Tire Identification Number on the sidewall; its last four digits are week and year. For 0109 that is the first full week of 2009. The number may be on only one side of the tire.
Where do I find the right tire size for my car?
On the Tire and Loading Information Label on the driver’s door edge or post, or in the owner’s manual (NHTSA). The tire dealer can help if you’re unsure.
Look up real ratings
- 225/65R17 tires ranked by treadwear35 graded lines
- 235/55R19 tires ranked by treadwear32 graded lines
- 215/65R16 tires ranked by treadwear33 graded lines
Sources
- Reading a Tire Sidewall, Tire Industry Association. Retrieved 2026-10-25.
- Tire Load Rating & Speed Rating Explained, Michelin USA. Retrieved 2026-10-25.
- 49 CFR § 574.5 Tire identification requirements, Cornell Legal Information Institute (text of the CFR). Retrieved 2026-10-25.
- 49 CFR § 575.104 Uniform tire quality grading standards, U.S. Code of Federal Regulations (eCFR). Retrieved 2026-10-25.
- TireWise: Tire Safety Ratings and Awareness, NHTSA. Retrieved 2026-10-25.
- Tire Replacement, Tire Industry Association. Retrieved 2026-10-25.
NHTSA ratings are from the dataset we publish. Maker statements are the makers’ own claims. We make no price claims. Found an error? See About & corrections.
Keep reading
- When to replace your tiresSafety
- What does a tire treadwear rating mean?UTQG basics
- How much do tires cost?Buying