285/40R20 tire size
A 285/40R20 tire is 28.98 inches (736.0 mm) tall, 11.22 in (285 mm) wide and fits a 20-inch wheel. In inch notation it is roughly a 29.0x11.2R20 — a "29-inch" tire.
| Overall diameter | 28.98 in | 736.0 mm |
|---|---|---|
| Section width | 11.22 in | 285 mm |
| Sidewall height | 4.49 in | 114.0 mm |
| Circumference | 91.03 in | 2,312 mm |
| Revolutions | 696.0 per mile | 432.5 per km |
| Rim diameter | 20 in | 508.0 mm |
Compare 285/40R20 with another size
Alternative sizes on the same 20-inch wheel
Sizes in use within ±3 % of the overall diameter of 285/40R20:
Plus and minus sizes for 285/40R20
| Size | Wheel | Diameter | Difference |
|---|---|---|---|
| 255/55R18 | Minus 2 (18 in) | 29.04 in | +0.23% |
| 285/50R18 | Minus 2 (18 in) | 29.22 in | +0.84% |
| 255/50R19 | Minus 1 (19 in) | 29.04 in | +0.22% |
| 285/45R19 | Minus 1 (19 in) | 29.10 in | +0.42% |
| 275/45R19 | Minus 1 (19 in) | 28.74 in | −0.80% |
| 265/50R19 | Minus 1 (19 in) | 29.43 in | +1.58% |
| 255/40R21 | Plus 1 (21 in) | 29.03 in | +0.19% |
| 335/30R21 | Plus 1 (21 in) | 28.91 in | −0.22% |
| 285/35R21 | Plus 1 (21 in) | 28.85 in | −0.42% |
| 295/35R21 | Plus 1 (21 in) | 29.13 in | +0.53% |
| 295/30R22 | Plus 2 (22 in) | 28.97 in | −0.03% |
| 255/35R22 | Plus 2 (22 in) | 29.03 in | +0.18% |
| 305/30R22 | Plus 2 (22 in) | 29.20 in | +0.79% |
| 285/30R22 | Plus 2 (22 in) | 28.73 in | −0.84% |
Vehicles approved with 285/40R20 tires
Models whose Swiss type approval lists 285/40R20 as a standard or optional size (413 approvals in total). Always check your own vehicle's placard or papers.
- BMW 7 Series
- Porsche Taycan
- Mercedes-Benz GLC
- Rolls-Royce Ghost
- Alfa Romeo Stelvio
- BMW i7
- Rolls-Royce Wraith
- Rolls-Royce Dawn
- Alpina XD3
- Alpina XD4
- Audi E-tron
- Lotus Emeya
- Jeep GdCherokee
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 20-inch sizes
- 265/30R20 (−9.4%)
- 265/35R20 (−5.8%)
- 265/40R20 (−2.2%)
- 265/45R20 (+1.4%)
- 265/50R20 (+5.0%)
- 275/30R20 (−8.6%)
- 275/35R20 (−4.8%)
- 275/40R20 (−1.1%)
- 275/45R20 (+2.6%)
- 275/50R20 (+6.4%)
- 285/30R20 (−7.7%)
- 285/35R20 (−3.9%)
- 285/45R20 (+3.9%)
- 285/50R20 (+7.7%)
- 295/30R20 (−6.9%)
- 295/35R20 (−2.9%)
- 295/40R20 (+1.1%)
- 295/45R20 (+5.1%)
- 305/30R20 (−6.1%)
- 305/35R20 (−2.0%)
- 305/40R20 (+2.2%)
Reading the 285/40R20 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).
- 20 — fits a 20-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.