34.2" tall, 10.8" wide, 8.1" sidewall
A 275/75R18 tire is 34.2 inches (870 mm) tall and 10.8 inches wide. The sidewall is 75% of the width, 8.1 inches, on a 18-inch wheel, and the tire turns about 589 times per mile.
In flotation terms that is about 34.2x10.8R18. People often call it a 34-inch tire.
The size most often compared with it is 295/70R18, which is 0.0" taller (+0.1%). At an indicated 60 mph you would be doing 60.0 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 275/75R18 | |
|---|---|---|---|---|---|
| 295/70R18 | 34.3" | 11.6" | 8.1" | +0.1% | |
| 255/80R18 | 34.1" | 10.0" | 8.0" | −0.5% | |
| 265/80R18 | 34.7" | 10.4" | 8.3" | +1.3% | |
| 285/70R18 | 33.7" | 11.2" | 7.9" | −1.6% | |
| 265/75R18 | 33.6" | 10.4" | 7.8" | −1.7% | |
| 285/75R18 | 34.8" | 11.2" | 8.4" | +1.7% | |
| 275/70R18 | 33.2" | 10.8" | 7.6" | −3.2% | |
| 275/80R18 | 35.3" | 10.8" | 8.7" | +3.2% | |
| 295/65R18 | 33.1" | 11.6" | 7.5" | −3.3% | |
| 255/75R18 | 33.1" | 10.0" | 7.5" | −3.4% |
Sizes within 2% of 34.2" on 17" or 16" or 20" wheels.
| Size | Diameter | Width | Sidewall | vs 275/75R18 | |
|---|---|---|---|---|---|
| 275/80R17 | 34.3" | 10.8" | 8.7" | +0.2% | |
| 315/70R17 | 34.4" | 12.4" | 8.7" | +0.4% | |
| 275/85R16 | 34.4" | 10.8" | 9.2" | +0.5% | |
| 275/65R20 | 34.1" | 10.8" | 7.0" | −0.5% | |
| 325/55R20 | 34.1" | 12.8" | 7.0" | −0.5% | |
| 305/60R20 | 34.4" | 12.0" | 7.2" | +0.5% |
Actual speed when the speedometer is calibrated for 275/75R18.
| Speedometer shows | on 295/70R18 | on 255/80R18 | on 265/80R18 |
|---|---|---|---|
| 30 mph | 30.0 mph | 29.8 mph | 30.4 mph |
| 45 mph | 45.0 mph | 44.8 mph | 45.6 mph |
| 60 mph | 60.0 mph | 59.7 mph | 60.8 mph |
| 70 mph | 70.0 mph | 69.6 mph | 70.9 mph |
34.2 inches (870 mm). The sidewall is 8.1 inches.
10.8 inches (275 mm) section width, measured sidewall to sidewall.
About 34.2x10.8R18.
295/70R18 is +0.1% in diameter, within the common 3% guideline. It is 0.8" wider.