27.9" tall, 11.2" wide, 3.9" sidewall
A 285/35R20 tire is 27.9 inches (708 mm) tall and 11.2 inches wide. The sidewall is 35% of the width, 3.9 inches, on a 20-inch wheel, and the tire turns about 724 times per mile.
In flotation terms that is about 27.9x11.2R20. People often call it a 28-inch tire.
The size most often compared with it is 275/35R20, which is 0.3" shorter (−1.0%). At an indicated 60 mph you would be doing 59.4 mph on it.
| Current | New | Difference |
|---|
| Shows | Actual speed |
|---|
Same 20" wheel, within 20 mm of width and 10 points of aspect ratio.
| Size | Diameter | Width | Sidewall | vs 285/35R20 | |
|---|---|---|---|---|---|
| 295/35R20 | 28.1" | 11.6" | 4.1" | +1.0% | |
| 275/35R20 | 27.6" | 10.8" | 3.8" | −1.0% | compare |
| 265/35R20 | 27.3" | 10.4" | 3.7" | −2.0% | |
| 305/30R20 | 27.2" | 12.0" | 3.6" | −2.3% | |
| 295/30R20 | 27.0" | 11.6" | 3.5" | −3.2% | |
| 295/40R20 | 29.3" | 11.6" | 4.6" | +5.2% | |
| 305/40R20 | 29.6" | 12.0" | 4.8" | +6.3% | |
| 295/45R20 | 30.5" | 11.6" | 5.2" | +9.3% | |
| 305/45R20 | 30.8" | 12.0" | 5.4" | +10.6% |
Sizes within 2% of 27.9" on 18" or 22" wheels.
| Size | Diameter | Width | Sidewall | vs 285/35R20 | |
|---|---|---|---|---|---|
| 275/45R18 | 27.7" | 10.8" | 4.9" | −0.4% | |
| 255/50R18 | 28.0" | 10.0" | 5.0" | +0.7% | |
| 285/45R18 | 28.1" | 11.2" | 5.0" | +0.9% | |
| 265/30R22 | 28.3" | 10.4" | 3.1" | +1.5% |
Actual speed when the speedometer is calibrated for 285/35R20.
| Speedometer shows | on 275/35R20 | on 295/35R20 | on 265/35R20 |
|---|---|---|---|
| 30 mph | 29.7 mph | 30.3 mph | 29.4 mph |
| 45 mph | 44.6 mph | 45.4 mph | 44.1 mph |
| 60 mph | 59.4 mph | 60.6 mph | 58.8 mph |
| 70 mph | 69.3 mph | 70.7 mph | 68.6 mph |
27.9 inches (708 mm). The sidewall is 3.9 inches.
11.2 inches (285 mm) section width, measured sidewall to sidewall.
About 27.9x11.2R20.
275/35R20 is −1.0% in diameter, within the common 3% guideline. It is 0.4" narrower.