31.8" tall, 11.2" wide, 8.4" sidewall
A 285/75R15 tire is 31.8 inches (809 mm) tall and 11.2 inches wide. The sidewall is 75% of the width, 8.4 inches, on a 15-inch wheel, and the tire turns about 634 times per mile.
In flotation terms that is about 31.8x11.2R15, closest to the common 32x11.50R15 (32.0"). People often call it a 32-inch tire.
The size most often compared with it is 305/70R15, which is 0.0" shorter (−0.1%). At an indicated 60 mph you would be doing 60.0 mph on it.
| Current | New | Difference |
|---|
| Shows | Actual speed |
|---|
Same 15" wheel, within 20 mm of width and 10 points of aspect ratio.
| Size | Diameter | Width | Sidewall | vs 285/75R15 | |
|---|---|---|---|---|---|
| 305/70R15 | 31.8" | 12.0" | 8.4" | −0.1% | |
| 32x11.50R15 | 32.0" | 11.5" | 8.5" | +0.5% | |
| 295/70R15 | 31.3" | 11.6" | 8.1" | −1.8% | |
| 275/75R15 | 31.2" | 10.8" | 8.1" | −1.9% | |
| 295/75R15 | 32.4" | 11.6" | 8.7" | +1.9% | |
| 31x10.50R15 | 31.0" | 10.5" | 8.0" | −2.6% | |
| 265/85R15 | 32.7" | 10.4" | 8.9" | +2.8% | |
| 285/70R15 | 30.7" | 11.2" | 7.9" | −3.5% | |
| 265/75R15 | 30.6" | 10.4" | 7.8" | −3.7% | |
| 275/70R15 | 30.2" | 10.8" | 7.6" | −5.3% |
Sizes within 2% of 31.8" on 17" or 16" wheels.
| Size | Diameter | Width | Sidewall | vs 285/75R15 | |
|---|---|---|---|---|---|
| 235/80R17 | 31.8" | 9.3" | 7.4" | −0.1% | |
| 315/60R17 | 31.9" | 12.4" | 7.4" | +0.2% | |
| 235/85R16 | 31.7" | 9.3" | 7.9" | −0.3% | |
| 285/70R16 | 31.7" | 11.2" | 7.9" | −0.4% | |
| 265/75R16 | 31.6" | 10.4" | 7.8" | −0.6% | |
| 265/70R17 | 31.6" | 10.4" | 7.3" | −0.7% |
Actual speed when the speedometer is calibrated for 285/75R15.
| Speedometer shows | on 305/70R15 | on 32x11.50R15 | on 295/70R15 |
|---|---|---|---|
| 30 mph | 30.0 mph | 30.2 mph | 29.5 mph |
| 45 mph | 45.0 mph | 45.2 mph | 44.2 mph |
| 60 mph | 60.0 mph | 60.3 mph | 58.9 mph |
| 70 mph | 70.0 mph | 70.4 mph | 68.7 mph |
31.8 inches (809 mm). The sidewall is 8.4 inches.
11.2 inches (285 mm) section width, measured sidewall to sidewall.
About 31.8x11.2R15; the closest common flotation size is 32x11.50R15 at 32.0".
305/70R15 is −0.1% in diameter, within the common 3% guideline. It is 0.8" wider.