205/45R18 tire size
A 205/45R18 tire is 25.26 inches (641.7 mm) tall, 8.07 in (205 mm) wide and fits a 18-inch wheel. In inch notation it is roughly a 25.3x8.1R18.
| Overall diameter | 25.26 in | 641.7 mm |
|---|---|---|
| Section width | 8.07 in | 205 mm |
| Sidewall height | 3.63 in | 92.3 mm |
| Circumference | 79.37 in | 2,016 mm |
| Revolutions | 798.3 per mile | 496.0 per km |
| Rim diameter | 18 in | 457.2 mm |
Compare 205/45R18 with another size
Alternative sizes on the same 18-inch wheel
Sizes in use within ±3 % of the overall diameter of 205/45R18:
Plus and minus sizes for 205/45R18
| Size | Wheel | Diameter | Difference |
|---|---|---|---|
| 235/50R16 | Minus 2 (16 in) | 25.25 in | −0.05% |
| 215/55R16 | Minus 2 (16 in) | 25.31 in | +0.19% |
| 195/60R16 | Minus 2 (16 in) | 25.21 in | −0.20% |
| 245/50R16 | Minus 2 (16 in) | 25.65 in | +1.51% |
| 235/45R17 | Minus 1 (17 in) | 25.33 in | +0.25% |
| 195/55R17 | Minus 1 (17 in) | 25.44 in | +0.72% |
| 205/50R17 | Minus 1 (17 in) | 25.07 in | −0.76% |
| 215/50R17 | Minus 1 (17 in) | 25.46 in | +0.79% |
| 225/35R19 | Plus 1 (19 in) | 25.20 in | −0.25% |
| 235/35R19 | Plus 1 (19 in) | 25.48 in | +0.84% |
| 255/30R19 | Plus 1 (19 in) | 25.02 in | −0.95% |
| 245/30R19 | Plus 1 (19 in) | 24.79 in | −1.89% |
| 245/30R20 | Plus 2 (20 in) | 25.79 in | +2.07% |
Vehicles approved with 205/45R18 tires
Models whose Swiss type approval lists 205/45R18 as a standard or optional size (1,255 approvals in total). Always check your own vehicle's placard or papers.
Source: Swiss Federal Roads Office (FEDRO/ASTRA), open government data. Original data (downloaded 2026-09-29). Data processed by us; errors in processing are ours, not the publisher's.
Nearby 18-inch sizes
Reading the 205/45R18 size
- 205 — section width in millimetres (8.07 in).
- 45 — aspect ratio: the sidewall is 45 % of the width, 92.3 mm.
- R — radial construction (ZR on the sidewall means a high-speed rated radial; the dimensions are the same).
- 18 — fits a 18-inch diameter wheel.
The load index and speed rating (for example 91V) follow the size on the sidewall. They must meet at least the values on your vehicle's tire placard.