33.6" tall, 12.4" wide, 9.3" sidewall
A 315/75R15 tire is 33.6 inches (854 mm) tall and 12.4 inches wide. The sidewall is 75% of the width, 9.3 inches, on a 15-inch wheel, and the tire turns about 600 times per mile.
In flotation terms that is about 33.6x12.4R15. People often call it a 34-inch tire.
The size most often compared with it is 33x12.50R15, which is 0.6" shorter (−1.8%). At an indicated 60 mph you would be doing 58.9 mph on it.
| 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 315/75R15 | |
|---|---|---|---|---|---|
| 33x12.50R15 | 33.0" | 12.5" | 9.0" | −1.8% | |
| 295/75R15 | 32.4" | 11.6" | 8.7" | −3.5% | |
| 315/70R15 | 32.4" | 12.4" | 8.7" | −3.7% | |
| 35x12.50R15 | 35.0" | 12.5" | 10.0" | +4.2% | |
| 305/70R15 | 31.8" | 12.0" | 8.4" | −5.3% | |
| 295/70R15 | 31.3" | 11.6" | 8.1" | −7.0% | |
| 295/65R15 | 30.1" | 11.6" | 7.5" | −10.4% |
Sizes within 2% of 33.6" on 17" or 16" wheels.
| Size | Diameter | Width | Sidewall | vs 315/75R15 | |
|---|---|---|---|---|---|
| 265/80R17 | 33.7" | 10.4" | 8.3" | +0.3% | |
| 265/85R16 | 33.7" | 10.4" | 8.9" | +0.4% | |
| 295/75R16 | 33.4" | 11.6" | 8.7" | −0.5% | |
| 245/85R17 | 33.4" | 9.6" | 8.2" | −0.6% | |
| 305/70R17 | 33.8" | 12.0" | 8.4" | +0.6% | |
| 285/75R17 | 33.8" | 11.2" | 8.4" | +0.7% |
Actual speed when the speedometer is calibrated for 315/75R15.
| Speedometer shows | on 33x12.50R15 | on 295/75R15 | on 315/70R15 |
|---|---|---|---|
| 30 mph | 29.5 mph | 28.9 mph | 28.9 mph |
| 45 mph | 44.2 mph | 43.4 mph | 43.3 mph |
| 60 mph | 58.9 mph | 57.9 mph | 57.8 mph |
| 70 mph | 68.7 mph | 67.5 mph | 67.4 mph |
33.6 inches (854 mm). The sidewall is 9.3 inches.
12.4 inches (315 mm) section width, measured sidewall to sidewall.
About 33.6x12.4R15.
33x12.50R15 is −1.8% in diameter, within the common 3% guideline. It is 0.1" wider.