29.1" tall, 10.0" wide, 7.0" sidewall
A 255/70R15 tire is 29.1 inches (738 mm) tall and 10.0 inches wide. The sidewall is 70% of the width, 7.0 inches, on a 15-inch wheel, and the tire turns about 694 times per mile.
In flotation terms that is about 29.1x10.0R15. People often call it a 29-inch tire.
The size most often compared with it is 275/60R15, which is 1.1" shorter (−3.7%). At an indicated 60 mph you would be doing 57.8 mph on it, more than the 3% change many shops use as a limit.
| Current | New | Difference |
|---|
| Shows | Actual speed |
|---|
Same 15" wheel, within 20 mm of width and 10 points of aspect ratio.
| Size | Diameter | Width | Sidewall | vs 255/70R15 | |
|---|---|---|---|---|---|
| 235/75R15 | 28.9" | 9.3" | 6.9" | −0.6% | compare |
| 245/75R15 | 29.5" | 9.6" | 7.2" | +1.4% | |
| 265/65R15 | 28.6" | 10.4" | 6.8" | −1.7% | |
| 245/70R15 | 28.5" | 9.6" | 6.8" | −1.9% | |
| 265/70R15 | 29.6" | 10.4" | 7.3" | +1.9% | |
| 30x9.50R15 | 30.0" | 9.5" | 7.5" | +3.3% | |
| 255/65R15 | 28.1" | 10.0" | 6.5" | −3.5% | |
| 255/75R15 | 30.1" | 10.0" | 7.5" | +3.5% | |
| 275/60R15 | 28.0" | 10.8" | 6.5" | −3.7% | compare |
| 235/70R15 | 28.0" | 9.3" | 6.5" | −3.8% |
Sizes within 2% of 29.1" on 16" or 17" wheels.
| Size | Diameter | Width | Sidewall | vs 255/70R15 | |
|---|---|---|---|---|---|
| 275/60R16 | 29.0" | 10.8" | 6.5" | −0.2% | |
| 205/80R16 | 28.9" | 8.1" | 6.5" | −0.5% | |
| 275/55R17 | 28.9" | 10.8" | 6.0" | −0.5% | |
| 225/75R16 | 29.3" | 8.9" | 6.6" | +0.8% | |
| 285/55R17 | 29.3" | 11.2" | 6.2" | +1.0% | |
| 225/70R17 | 29.4" | 8.9" | 6.2" | +1.2% |
Actual speed when the speedometer is calibrated for 255/70R15.
| Speedometer shows | on 275/60R15 | on 255/60R15 | on 235/75R15 |
|---|---|---|---|
| 30 mph | 28.9 mph | 27.9 mph | 29.8 mph |
| 45 mph | 43.4 mph | 41.9 mph | 44.7 mph |
| 60 mph | 57.8 mph | 55.9 mph | 59.6 mph |
| 70 mph | 67.4 mph | 65.2 mph | 69.6 mph |
29.1 inches (738 mm). The sidewall is 7.0 inches.
10.0 inches (255 mm) section width, measured sidewall to sidewall.
About 29.1x10.0R15.
275/60R15 is −3.7% in diameter, more than the common 3% guideline, so expect a speedometer error and check clearance. It is 0.8" wider.