255/70R18 tire size
A 255/70R18 tire is 32.06 inches (814.2 mm) tall, 10.04 in (255 mm) wide and fits a 18-inch wheel. In inch notation it is roughly a 32.1x10.0R18 — a "32-inch" tire.
| Overall diameter | 32.06 in | 814.2 mm |
|---|---|---|
| Section width | 10.04 in | 255 mm |
| Sidewall height | 7.03 in | 178.5 mm |
| Circumference | 100.70 in | 2,558 mm |
| Revolutions | 629.2 per mile | 390.9 per km |
| Rim diameter | 18 in | 457.2 mm |
Compare 255/70R18 with another size
Alternative sizes on the same 18-inch wheel
Sizes in use within ±3 % of the overall diameter of 255/70R18:
Plus and minus sizes for 255/70R18
| Size | Wheel | Diameter | Difference |
|---|---|---|---|
| 235/85R16 | Minus 2 (16 in) | 31.73 in | −1.02% |
| 265/75R16 | Minus 2 (16 in) | 31.65 in | −1.27% |
| 285/75R16 | Minus 2 (16 in) | 32.83 in | +2.42% |
| 275/70R16 | Minus 2 (16 in) | 31.16 in | −2.80% |
| 255/75R17 | Minus 1 (17 in) | 32.06 in | +0.01% |
| 235/80R17 | Minus 1 (17 in) | 31.80 in | −0.79% |
| 265/70R17 | Minus 1 (17 in) | 31.61 in | −1.40% |
| 285/65R17 | Minus 1 (17 in) | 31.59 in | −1.46% |
| 255/65R19 | Plus 1 (19 in) | 32.05 in | −0.01% |
| 255/60R20 | Plus 2 (20 in) | 32.05 in | −0.02% |
| 275/55R20 | Plus 2 (20 in) | 31.91 in | −0.45% |
| 285/55R20 | Plus 2 (20 in) | 32.34 in | +0.90% |
| 265/60R20 | Plus 2 (20 in) | 32.52 in | +1.45% |
| 275/50R21 | Plus 3 (21 in) | 31.83 in | −0.71% |
| 245/55R21 | Plus 3 (21 in) | 31.61 in | −1.39% |
| 285/45R21 | Plus 3 (21 in) | 31.10 in | −2.98% |
Vehicles approved with 255/70R18 tires
Models whose Swiss type approval lists 255/70R18 as a standard or optional size (297 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 255/70R18 size
- 255 — section width in millimetres (10.04 in).
- 70 — aspect ratio: the sidewall is 70 % of the width, 178.5 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.