255/40R20 tire size
A 255/40R20 tire is 28.03 inches (712.0 mm) tall, 10.04 in (255 mm) wide and fits a 20-inch wheel. In inch notation it is roughly a 28.0x10.0R20 — a "28-inch" tire.
| Overall diameter | 28.03 in | 712.0 mm |
|---|---|---|
| Section width | 10.04 in | 255 mm |
| Sidewall height | 4.02 in | 102.0 mm |
| Circumference | 88.06 in | 2,237 mm |
| Revolutions | 719.5 per mile | 447.1 per km |
| Rim diameter | 20 in | 508.0 mm |
Compare 255/40R20 with another size
Alternative sizes on the same 20-inch wheel
Sizes in use within ±3 % of the overall diameter of 255/40R20:
Plus and minus sizes for 255/40R20
| Size | Wheel | Diameter | Difference |
|---|---|---|---|
| 255/50R18 | Minus 2 (18 in) | 28.04 in | +0.03% |
| 285/45R18 | Minus 2 (18 in) | 28.10 in | +0.24% |
| 235/55R18 | Minus 2 (18 in) | 28.18 in | +0.52% |
| 275/45R18 | Minus 2 (18 in) | 27.74 in | −1.03% |
| 255/45R19 | Minus 1 (19 in) | 28.04 in | +0.01% |
| 285/40R19 | Minus 1 (19 in) | 27.98 in | −0.20% |
| 225/50R19 | Minus 1 (19 in) | 27.86 in | −0.62% |
| 235/50R19 | Minus 1 (19 in) | 28.25 in | +0.79% |
| 255/35R21 | Plus 1 (21 in) | 28.03 in | −0.01% |
| 295/30R21 | Plus 1 (21 in) | 27.97 in | −0.22% |
| 305/30R21 | Plus 1 (21 in) | 28.20 in | +0.62% |
| 265/35R21 | Plus 1 (21 in) | 28.30 in | +0.97% |
| 285/30R22 | Plus 2 (22 in) | 28.73 in | +2.50% |
Vehicles approved with 255/40R20 tires
Models whose Swiss type approval lists 255/40R20 as a standard or optional size (2,663 approvals in total). Always check your own vehicle's placard or papers.
- Volkswagen Tiguan
- Audi A6
- Audi A7
- Audi Q3
- Mercedes-Benz S-Class
- Skoda Kodiaq
- Audi Q5
- Porsche Panamera
- Mercedes-Benz GLK
- Audi S6
- Porsche Taycan
- Audi RS
- Tesla Model Y
- Aston Martin DB11
- SEAT Tarraco
- Nissan GT-R
- Audi S7
- Aston Martin Vantage
- Volvo XC40
- Volvo C40
- Volvo EX40
- Mercedes-Benz GLB
- Zeekr 7GT
- Mercedes-Benz GLA
- Bentley Arnage
- Bentley Conti
- Mercedes-Benz EQE
- Bentley Continental
- Bentley Cont
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
- 235/35R20 (−5.5%)
- 235/40R20 (−2.2%)
- 235/45R20 (+1.1%)
- 235/50R20 (+4.4%)
- 245/30R20 (−8.0%)
- 245/35R20 (−4.6%)
- 245/40R20 (−1.1%)
- 245/45R20 (+2.3%)
- 245/50R20 (+5.8%)
- 255/30R20 (−7.2%)
- 255/35R20 (−3.6%)
- 255/45R20 (+3.6%)
- 255/50R20 (+7.2%)
- 265/30R20 (−6.3%)
- 265/35R20 (−2.6%)
- 265/40R20 (+1.1%)
- 265/45R20 (+4.8%)
- 265/50R20 (+8.6%)
- 275/30R20 (−5.5%)
- 275/35R20 (−1.6%)
- 275/40R20 (+2.2%)
- 275/45R20 (+6.1%)
- 275/50R20 (+10.0%)
Reading the 255/40R20 size
- 255 — section width in millimetres (10.04 in).
- 40 — aspect ratio: the sidewall is 40 % of the width, 102.0 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.