31.5" tall, 11.2" wide, 6.7" sidewall
A 285/60R18 tire is 31.5 inches (799 mm) tall and 11.2 inches wide. The sidewall is 60% of the width, 6.7 inches, on a 18-inch wheel, and the tire turns about 641 times per mile.
In flotation terms that is about 31.5x11.2R18. People often call it a 31-inch tire.
The size most often compared with it is 285/65R18, which is 1.1" taller (+3.6%). At an indicated 60 mph you would be doing 62.1 mph on it, more than the 3% change many shops use as a limit.
| Current | New | Difference |
|---|
| Shows | Actual speed |
|---|
Same 18" wheel, within 20 mm of width and 10 points of aspect ratio.
| Size | Diameter | Width | Sidewall | vs 285/60R18 | |
|---|---|---|---|---|---|
| 265/65R18 | 31.6" | 10.4" | 6.8" | +0.3% | |
| 305/55R18 | 31.2" | 12.0" | 6.6" | −0.8% | |
| 275/60R18 | 31.0" | 10.8" | 6.5" | −1.5% | |
| 295/60R18 | 31.9" | 11.6" | 7.0" | +1.5% | |
| 275/65R18 | 32.1" | 10.8" | 7.0" | +1.9% | |
| 295/55R18 | 30.8" | 11.6" | 6.4" | −2.2% | |
| 305/60R18 | 32.4" | 12.0" | 7.2" | +3.0% | |
| 285/55R18 | 30.3" | 11.2" | 6.2" | −3.6% | |
| 285/65R18 | 32.6" | 11.2" | 7.3" | +3.6% | compare |
| 265/70R18 | 32.6" | 10.4" | 7.3" | +3.6% |
Sizes within 2% of 31.5" on 17" or 20" or 16" or 19" wheels.
| Size | Diameter | Width | Sidewall | vs 285/60R18 | |
|---|---|---|---|---|---|
| 245/75R17 | 31.5" | 9.6" | 7.2" | +0.0% | |
| 265/55R20 | 31.5" | 10.4" | 5.7" | +0.0% | |
| 245/80R16 | 31.4" | 9.6" | 7.7" | −0.1% | |
| 305/60R17 | 31.4" | 12.0" | 7.2" | −0.2% | |
| 225/70R19 | 31.4" | 8.9" | 6.2" | −0.2% | |
| 245/60R20 | 31.6" | 9.6" | 5.8" | +0.4% |
Actual speed when the speedometer is calibrated for 285/60R18.
| Speedometer shows | on 285/65R18 | on 285/70R17 | on 265/65R18 |
|---|---|---|---|
| 30 mph | 31.1 mph | 31.2 mph | 30.1 mph |
| 45 mph | 46.6 mph | 46.8 mph | 45.1 mph |
| 60 mph | 62.1 mph | 62.4 mph | 60.2 mph |
| 70 mph | 72.5 mph | 72.8 mph | 70.2 mph |
31.5 inches (799 mm). The sidewall is 6.7 inches.
11.2 inches (285 mm) section width, measured sidewall to sidewall.
About 31.5x11.2R18.
285/65R18 is +3.6% in diameter, more than the common 3% guideline, so expect a speedometer error and check clearance. It is 0.0" wider.