275/40R21 tire size
A 275/40R21 tire is 29.66 inches (753.4 mm) tall, 10.83 in (275 mm) wide and fits a 21-inch wheel. In inch notation it is roughly a 29.7x10.8R21 — a "30-inch" tire.
| Overall diameter | 29.66 in | 753.4 mm |
|---|---|---|
| Section width | 10.83 in | 275 mm |
| Sidewall height | 4.33 in | 110.0 mm |
| Circumference | 93.18 in | 2,367 mm |
| Revolutions | 679.9 per mile | 422.5 per km |
| Rim diameter | 21 in | 533.4 mm |
Compare 275/40R21 with another size
Alternative sizes on the same 21-inch wheel
Sizes in use within ±3 % of the overall diameter of 275/40R21:
Plus and minus sizes for 275/40R21
| Size | Wheel | Diameter | Difference |
|---|---|---|---|
| 275/50R19 | Minus 2 (19 in) | 29.83 in | +0.56% |
| 295/45R19 | Minus 2 (19 in) | 29.45 in | −0.70% |
| 265/50R19 | Minus 2 (19 in) | 29.43 in | −0.77% |
| 255/55R19 | Minus 2 (19 in) | 30.04 in | +1.29% |
| 245/50R20 | Minus 1 (20 in) | 29.65 in | −0.05% |
| 305/40R20 | Minus 1 (20 in) | 29.61 in | −0.19% |
| 275/45R20 | Minus 1 (20 in) | 29.74 in | +0.28% |
| 265/45R20 | Minus 1 (20 in) | 29.39 in | −0.92% |
| 275/35R22 | Plus 1 (22 in) | 29.58 in | −0.28% |
| 285/35R22 | Plus 1 (22 in) | 29.85 in | +0.65% |
| 315/30R22 | Plus 1 (22 in) | 29.44 in | −0.74% |
| 265/35R22 | Plus 1 (22 in) | 29.30 in | −1.21% |
| 315/30R23 | Plus 2 (23 in) | 30.44 in | +2.63% |
Vehicles approved with 275/40R21 tires
Models whose Swiss type approval lists 275/40R21 as a standard or optional size (2,303 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
- 255/35R21 (−5.5%)
- 255/40R21 (−2.1%)
- 255/45R21 (+1.3%)
- 255/50R21 (+4.6%)
- 265/30R21 (−8.1%)
- 265/35R21 (−4.6%)
- 265/40R21 (−1.1%)
- 265/45R21 (+2.5%)
- 275/30R21 (−7.3%)
- 275/35R21 (−3.7%)
- 275/45R21 (+3.7%)
- 275/50R21 (+7.3%)
- 285/30R21 (−6.5%)
- 285/35R21 (−2.7%)
- 285/40R21 (+1.1%)
- 285/45R21 (+4.8%)
- 295/30R21 (−5.7%)
- 295/35R21 (−1.8%)
- 295/40R21 (+2.1%)
Reading the 275/40R21 size
- 275 — section width in millimetres (10.83 in).
- 40 — aspect ratio: the sidewall is 40 % of the width, 110.0 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.