255/45R18 tire size
A 255/45R18 tire is 27.04 inches (686.7 mm) tall, 10.04 in (255 mm) wide and fits a 18-inch wheel. In inch notation it is roughly a 27.0x10.0R18.
| Overall diameter | 27.04 in | 686.7 mm |
|---|---|---|
| Section width | 10.04 in | 255 mm |
| Sidewall height | 4.52 in | 114.8 mm |
| Circumference | 84.93 in | 2,157 mm |
| Revolutions | 746.0 per mile | 463.5 per km |
| Rim diameter | 18 in | 457.2 mm |
Compare 255/45R18 with another size
Alternative sizes on the same 18-inch wheel
Sizes in use within ±3 % of the overall diameter of 255/45R18:
Plus and minus sizes for 255/45R18
| Size | Wheel | Diameter | Difference |
|---|---|---|---|
| 235/60R16 | Minus 2 (16 in) | 27.10 in | +0.25% |
| 225/60R16 | Minus 2 (16 in) | 26.63 in | −1.50% |
| 245/55R16 | Minus 2 (16 in) | 26.61 in | −1.57% |
| 225/65R16 | Minus 2 (16 in) | 27.52 in | +1.78% |
| 235/55R17 | Minus 1 (17 in) | 27.18 in | +0.52% |
| 225/55R17 | Minus 1 (17 in) | 26.74 in | −1.08% |
| 245/50R17 | Minus 1 (17 in) | 26.65 in | −1.44% |
| 245/55R17 | Minus 1 (17 in) | 27.61 in | +2.13% |
| 255/40R19 | Plus 1 (19 in) | 27.03 in | −0.01% |
| 225/45R19 | Plus 1 (19 in) | 26.97 in | −0.23% |
| 295/35R19 | Plus 1 (19 in) | 27.13 in | +0.35% |
| 285/35R19 | Plus 1 (19 in) | 26.85 in | −0.67% |
| 255/35R20 | Plus 2 (20 in) | 27.03 in | −0.03% |
| 225/40R20 | Plus 2 (20 in) | 27.09 in | +0.19% |
| 295/30R20 | Plus 2 (20 in) | 26.97 in | −0.25% |
| 305/30R20 | Plus 2 (20 in) | 27.20 in | +0.63% |
| 265/30R21 | Plus 3 (21 in) | 27.26 in | +0.83% |
| 295/25R21 | Plus 3 (21 in) | 26.81 in | −0.84% |
| 275/30R21 | Plus 3 (21 in) | 27.50 in | +1.70% |
| 285/30R21 | Plus 3 (21 in) | 27.73 in | +2.58% |
Vehicles approved with 255/45R18 tires
Models whose Swiss type approval lists 255/45R18 as a standard or optional size (739 approvals in total). Always check your own vehicle's placard or papers.
- BMW 3 Series
- Mercedes-Benz S-Class
- Audi A7
- Volkswagen T5
- Volkswagen T6
- BMW X3
- Volkswagen Phaeton
- Cadillac STS
- Mercedes-Benz CL
- BMW i4
- BMW 7 Series
- Jaguar XK8
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
- 235/35R18 (−9.5%)
- 235/40R18 (−6.0%)
- 235/45R18 (−2.6%)
- 235/50R18 (+0.8%)
- 235/55R18 (+4.2%)
- 245/35R18 (−8.4%)
- 245/40R18 (−4.9%)
- 245/45R18 (−1.3%)
- 245/50R18 (+2.3%)
- 255/35R18 (−7.4%)
- 255/40R18 (−3.7%)
- 255/50R18 (+3.7%)
- 255/55R18 (+7.4%)
- 265/35R18 (−6.4%)
- 265/40R18 (−2.5%)
- 265/45R18 (+1.3%)
- 275/35R18 (−5.4%)
- 275/40R18 (−1.4%)
- 275/45R18 (+2.6%)
Reading the 255/45R18 size
- 255 — section width in millimetres (10.04 in).
- 45 — aspect ratio: the sidewall is 45 % of the width, 114.8 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.