34.1" tall, 10.0" wide, 8.5" sidewall
A 255/85R17 tire is 34.1 inches (865 mm) tall and 10.0 inches wide. The sidewall is 85% of the width, 8.5 inches, on a 17-inch wheel, and the tire turns about 592 times per mile.
In flotation terms that is about 34.1x10.0R17. People often call it a 34-inch tire.
The size most often compared with it is 275/80R17, which is 0.3" taller (+0.8%). At an indicated 60 mph you would be doing 60.5 mph on it.
| Current | New | Difference |
|---|
| Shows | Actual speed |
|---|
Same 17" wheel, within 20 mm of width and 10 points of aspect ratio.
| Size | Diameter | Width | Sidewall | vs 255/85R17 | |
|---|---|---|---|---|---|
| 275/80R17 | 34.3" | 10.8" | 8.7" | +0.8% | |
| 265/80R17 | 33.7" | 10.4" | 8.3" | −1.1% | |
| 245/85R17 | 33.4" | 9.6" | 8.2" | −2.0% | |
| 265/85R17 | 34.7" | 10.4" | 8.9" | +2.0% | |
| 255/80R17 | 33.1" | 10.0" | 8.0" | −2.9% | |
| 235/85R17 | 32.7" | 9.3" | 7.9" | −3.9% | |
| 275/85R17 | 35.4" | 10.8" | 9.2" | +3.9% | |
| 265/75R17 | 32.6" | 10.4" | 7.8" | −4.2% | |
| 245/80R17 | 32.4" | 9.6" | 7.7" | −4.8% | |
| 255/75R17 | 32.1" | 10.0" | 7.5" | −5.9% |
Sizes within 2% of 34.1" on 18" or 16" wheels.
| Size | Diameter | Width | Sidewall | vs 255/85R17 | |
|---|---|---|---|---|---|
| 255/80R18 | 34.1" | 10.0" | 8.0" | −0.0% | |
| 305/75R16 | 34.0" | 12.0" | 9.0" | −0.2% | |
| 315/65R18 | 34.1" | 12.4" | 8.1" | +0.2% | |
| 285/80R16 | 34.0" | 11.2" | 9.0" | −0.3% | |
| 275/75R18 | 34.2" | 10.8" | 8.1" | +0.5% | |
| 295/70R18 | 34.3" | 11.6" | 8.1" | +0.6% |
Actual speed when the speedometer is calibrated for 255/85R17.
| Speedometer shows | on 275/80R17 | on 265/80R17 | on 245/85R17 |
|---|---|---|---|
| 30 mph | 30.2 mph | 29.7 mph | 29.4 mph |
| 45 mph | 45.3 mph | 44.5 mph | 44.1 mph |
| 60 mph | 60.5 mph | 59.3 mph | 58.8 mph |
| 70 mph | 70.5 mph | 69.2 mph | 68.6 mph |
34.1 inches (865 mm). The sidewall is 8.5 inches.
10.0 inches (255 mm) section width, measured sidewall to sidewall.
About 34.1x10.0R17.
275/80R17 is +0.8% in diameter, within the common 3% guideline. It is 0.8" wider.