31.0" tall, 10.8" wide, 6.5" sidewall
A 275/60R18 tire is 31.0 inches (787 mm) tall and 10.8 inches wide. The sidewall is 60% of the width, 6.5 inches, on a 18-inch wheel, and the tire turns about 651 times per mile.
In flotation terms that is about 31.0x10.8R18. People often call it a 31-inch tire.
The size most often compared with it is 265/65R18, which is 0.6" taller (+1.8%). At an indicated 60 mph you would be doing 61.1 mph on it.
| 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 275/60R18 | |
|---|---|---|---|---|---|
| 295/55R18 | 30.8" | 11.6" | 6.4" | −0.7% | |
| 285/60R18 | 31.5" | 11.2" | 6.7" | +1.5% | |
| 265/65R18 | 31.6" | 10.4" | 6.8" | +1.8% | compare |
| 285/55R18 | 30.3" | 11.2" | 6.2" | −2.1% | |
| 295/60R18 | 31.9" | 11.6" | 7.0" | +3.0% | |
| 255/70R18 | 32.1" | 10.0" | 7.0" | +3.4% | |
| 275/55R18 | 29.9" | 10.8" | 6.0" | −3.5% | |
| 275/65R18 | 32.1" | 10.8" | 7.0" | +3.5% | |
| 265/55R18 | 29.5" | 10.4" | 5.7" | −4.9% | |
| 285/65R18 | 32.6" | 11.2" | 7.3" | +5.1% |
Sizes within 2% of 31.0" on 17" or 16" or 20" wheels.
| Size | Diameter | Width | Sidewall | vs 275/60R18 | |
|---|---|---|---|---|---|
| 255/70R17 | 31.1" | 10.0" | 7.0" | +0.2% | |
| 225/85R16 | 31.1" | 8.9" | 7.5" | +0.2% | |
| 255/75R16 | 31.1" | 10.0" | 7.5" | +0.2% | |
| 275/65R17 | 31.1" | 10.8" | 7.0" | +0.3% | |
| 275/70R16 | 31.2" | 10.8" | 7.6" | +0.5% | |
| 275/50R20 | 30.8" | 10.8" | 5.4" | −0.5% |
Actual speed when the speedometer is calibrated for 275/60R18.
| Speedometer shows | on 265/65R18 | on 295/55R18 | on 285/60R18 |
|---|---|---|---|
| 30 mph | 30.6 mph | 29.8 mph | 30.5 mph |
| 45 mph | 45.8 mph | 44.7 mph | 45.7 mph |
| 60 mph | 61.1 mph | 59.6 mph | 60.9 mph |
| 70 mph | 71.3 mph | 69.5 mph | 71.1 mph |
31.0 inches (787 mm). The sidewall is 6.5 inches.
10.8 inches (275 mm) section width, measured sidewall to sidewall.
About 31.0x10.8R18.
265/65R18 is +1.8% in diameter, within the common 3% guideline. It is 0.4" narrower.