285/40R21 tire size
A 285/40R21 tire is 29.98 inches (761.4 mm) tall, 11.22 in (285 mm) wide and fits a 21-inch wheel. In inch notation it is roughly a 30.0x11.2R21 — a "30-inch" tire.
| Overall diameter | 29.98 in | 761.4 mm |
|---|---|---|
| Section width | 11.22 in | 285 mm |
| Sidewall height | 4.49 in | 114.0 mm |
| Circumference | 94.17 in | 2,392 mm |
| Revolutions | 672.8 per mile | 418.1 per km |
| Rim diameter | 21 in | 533.4 mm |
Compare 285/40R21 with another size
Alternative sizes on the same 21-inch wheel
Sizes in use within ±3 % of the overall diameter of 285/40R21:
Plus and minus sizes for 285/40R21
| Size | Wheel | Diameter | Difference |
|---|---|---|---|
| 255/55R19 | Minus 2 (19 in) | 30.04 in | +0.22% |
| 275/50R19 | Minus 2 (19 in) | 29.83 in | −0.50% |
| 265/55R19 | Minus 2 (19 in) | 30.48 in | +1.67% |
| 295/45R19 | Minus 2 (19 in) | 29.45 in | −1.75% |
| 255/50R20 | Minus 1 (20 in) | 30.04 in | +0.21% |
| 285/45R20 | Minus 1 (20 in) | 30.10 in | +0.41% |
| 275/45R20 | Minus 1 (20 in) | 29.74 in | −0.77% |
| 305/40R20 | Minus 1 (20 in) | 29.61 in | −1.23% |
| 255/40R22 | Plus 1 (22 in) | 30.03 in | +0.18% |
| 285/35R22 | Plus 1 (22 in) | 29.85 in | −0.41% |
| 295/35R22 | Plus 1 (22 in) | 30.13 in | +0.51% |
| 265/40R22 | Plus 1 (22 in) | 30.35 in | +1.23% |
| 315/30R23 | Plus 2 (23 in) | 30.44 in | +1.55% |
| 275/35R23 | Plus 2 (23 in) | 30.58 in | +2.01% |
| 325/30R23 | Plus 2 (23 in) | 30.68 in | +2.34% |
| 285/35R23 | Plus 2 (23 in) | 30.85 in | +2.93% |
Vehicles approved with 285/40R21 tires
Models whose Swiss type approval lists 285/40R21 as a standard or optional size (1,142 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
- 265/30R21 (−9.1%)
- 265/35R21 (−5.6%)
- 265/40R21 (−2.1%)
- 265/45R21 (+1.4%)
- 275/30R21 (−8.3%)
- 275/35R21 (−4.7%)
- 275/40R21 (−1.1%)
- 275/45R21 (+2.6%)
- 275/50R21 (+6.2%)
- 285/30R21 (−7.5%)
- 285/35R21 (−3.7%)
- 285/45R21 (+3.7%)
- 295/30R21 (−6.7%)
- 295/35R21 (−2.8%)
- 295/40R21 (+1.1%)
- 305/30R21 (−5.9%)
- 305/35R21 (−1.9%)
- 305/40R21 (+2.1%)
Reading the 285/40R21 size
- 285 — section width in millimetres (11.22 in).
- 40 — aspect ratio: the sidewall is 40 % of the width, 114.0 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.