285/30R21 tire size
A 285/30R21 tire is 27.73 inches (704.4 mm) tall, 11.22 in (285 mm) wide and fits a 21-inch wheel. In inch notation it is roughly a 27.7x11.2R21 — a "28-inch" tire.
| Overall diameter | 27.73 in | 704.4 mm |
|---|---|---|
| Section width | 11.22 in | 285 mm |
| Sidewall height | 3.37 in | 85.5 mm |
| Circumference | 87.12 in | 2,213 mm |
| Revolutions | 727.2 per mile | 451.9 per km |
| Rim diameter | 21 in | 533.4 mm |
Compare 285/30R21 with another size
Alternative sizes on the same 21-inch wheel
Sizes in use within ±3 % of the overall diameter of 285/30R21:
Plus and minus sizes for 285/30R21
| Size | Wheel | Diameter | Difference |
|---|---|---|---|
| 275/40R19 | Minus 2 (19 in) | 27.66 in | −0.26% |
| 285/40R19 | Minus 2 (19 in) | 27.98 in | +0.88% |
| 255/45R19 | Minus 2 (19 in) | 28.04 in | +1.09% |
| 305/35R19 | Minus 2 (19 in) | 27.41 in | −1.18% |
| 325/30R20 | Minus 1 (20 in) | 27.68 in | −0.20% |
| 285/35R20 | Minus 1 (20 in) | 27.85 in | +0.44% |
| 275/35R20 | Minus 1 (20 in) | 27.58 in | −0.55% |
| 335/30R20 | Minus 1 (20 in) | 27.91 in | +0.65% |
Vehicles approved with 285/30R21 tires
Models whose Swiss type approval lists 285/30R21 as a standard or optional size (117 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 21-inch sizes
Reading the 285/30R21 size
- 285 — section width in millimetres (11.22 in).
- 30 — aspect ratio: the sidewall is 30 % of the width, 85.5 mm.
- R — radial construction (ZR on the sidewall means a high-speed rated radial; the dimensions are the same).
- 21 — fits a 21-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.