205/55R16 means a 205 mm section width, a 55% aspect ratio, radial construction and a 16-inch wheel. That works out to a 112.8 mm sidewall and an overall diameter of about 631.9 mm.
The aspect ratio is a proportion, not a measurement: the same 45 gives a different sidewall height on a different width, and that changes both ride and handling. A lower ratio holds a corner better and transmits more of the road surface.
The default fitment on compact cars such as the Avante, Niro and Golf.
What each number means
| 205 | Section width 205 mm |
|---|---|
| 55 | Aspect ratio 112.8 mm (55% × 205 mm) |
| R | Construction Radial |
| 16 | Wheel diameter 406.4 mm |
| Overall diameter | 631.9 mm 24.9" |
Compatible alternatives
| Size | Overall diameter | Diameter difference |
|---|---|---|
| 195/60R16 | 640.4 mm | +1.3% |
| 215/55R16 | 642.9 mm | +1.7% |
| 205/60R16 | 652.4 mm | +3.2% |
Load index and speed rating
After the size itself, a tyre wall carries something like 91V. The number is the load index — the weight one tyre can carry, 91 meaning 615 kg — and the letter is the speed rating, V meaning 240 km/h.
Never drop below the load index the manufacturer specified, even if the size matches. The original specification is printed on the label inside the driver’s door.