31.1" tall, 10.0" wide, 7.0" sidewall
A 255/70R17 tire is 31.1 inches (789 mm) tall and 10.0 inches wide. The sidewall is 70% of the width, 7.0 inches, on a 17-inch wheel, and the tire turns about 649 times per mile.
In flotation terms that is about 31.1x10.0R17. People often call it a 31-inch tire.
The size most often compared with it is 255/75R17, which is 1.0" taller (+3.2%). At an indicated 60 mph you would be doing 61.9 mph on it, more than the 3% change many shops use as a limit.
| 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 255/70R17 | |
|---|---|---|---|---|---|
| 275/65R17 | 31.1" | 10.8" | 7.0" | +0.1% | |
| 245/75R17 | 31.5" | 9.6" | 7.2" | +1.3% | |
| 265/65R17 | 30.6" | 10.4" | 6.8" | −1.6% | |
| 245/70R17 | 30.5" | 9.6" | 6.8" | −1.8% | |
| 265/70R17 | 31.6" | 10.4" | 7.3" | +1.8% | |
| 235/80R17 | 31.8" | 9.3" | 7.4" | +2.4% | |
| 255/65R17 | 30.1" | 10.0" | 6.5" | −3.2% | |
| 255/75R17 | 32.1" | 10.0" | 7.5" | +3.2% | compare |
| 275/60R17 | 30.0" | 10.8" | 6.5" | −3.4% | |
| 235/70R17 | 30.0" | 9.3" | 6.5" | −3.5% |
Sizes within 2% of 31.1" on 16" or 15" or 18" wheels.
| Size | Diameter | Width | Sidewall | vs 255/70R17 | |
|---|---|---|---|---|---|
| 225/85R16 | 31.1" | 8.9" | 7.5" | +0.0% | |
| 255/75R16 | 31.1" | 10.0" | 7.5" | +0.0% | |
| 31x10.50R15 | 31.0" | 10.5" | 8.0" | −0.2% | |
| 275/60R18 | 31.0" | 10.8" | 6.5" | −0.2% | |
| 275/70R16 | 31.2" | 10.8" | 7.6" | +0.3% | |
| 305/55R18 | 31.2" | 12.0" | 6.6" | +0.5% |
Actual speed when the speedometer is calibrated for 255/70R17.
| Speedometer shows | on 255/75R17 | on 255/80R17 | on 275/65R17 |
|---|---|---|---|
| 30 mph | 31.0 mph | 31.9 mph | 30.0 mph |
| 45 mph | 46.5 mph | 47.9 mph | 45.0 mph |
| 60 mph | 61.9 mph | 63.9 mph | 60.0 mph |
| 70 mph | 72.3 mph | 74.5 mph | 70.0 mph |
31.1 inches (789 mm). The sidewall is 7.0 inches.
10.0 inches (255 mm) section width, measured sidewall to sidewall.
About 31.1x10.0R17.
255/75R17 is +3.2% in diameter, more than the common 3% guideline, so expect a speedometer error and check clearance. It is 0.0" wider.