Tire size codes explained (205/55R16)
A tire code reads left to right: width in mm, sidewall height as a percentage of width, construction letter, rim diameter in inches, then load index and speed letter. Example: 205/55R16 91V.
| Code segment | Example | Meaning |
|---|---|---|
| 205 | 205 | Section width: tire is 205 mm wide at its widest point |
| /55 | 55 | Aspect ratio: sidewall height is 55% of width (≈113 mm) |
| R | R | Construction: R = radial (B = bias-belted, D = diagonal) |
| 16 | 16 | Rim diameter: fits a 16-inch wheel |
| 91 | 91 | Load index: 91 = 615 kg max load per tire |
| V | V | Speed rating: V = rated to 240 km/h (149 mph) |
| M+S / 3PMSF | M+S | Mud+Snow marking; 3PMSF snowflake = tested winter tire |
Notes
- Total tire diameter ≈ rim + 2 × sidewall: 16 in + 2 × 113 mm ≈ 632 mm for the example.
- Load index and speed rating must meet or exceed the placard values on the driver's door jamb.
- Winter tires may have a lower speed rating than the OEM tire — it's legal in most countries with a sticker reminder.
Frequently asked questions
- What does 205/55R16 mean?
- A radial tire 205 mm wide, with sidewall height 55% of that width, mounted on a 16-inch rim. Add the load/speed (e.g. 91V) for the full code.
- Can I change the tire aspect ratio?
- Within limits — the overall diameter must stay close (usually ±3%) so speedometer, gearing and clearance work as designed.
- What does the load index 91 mean?
- Each tire can carry up to 615 kg at maximum pressure; four tires support 2460 kg total.