32.4" tall, 12.4" wide, 8.7" sidewall
A 315/70R15 tire is 32.4 inches (822 mm) tall and 12.4 inches wide. The sidewall is 70% of the width, 8.7 inches, on a 15-inch wheel, and the tire turns about 623 times per mile.
In flotation terms that is about 32.4x12.4R15, closest to the common 32x11.50R15 (32.0"). People often call it a 32-inch tire.
The size most often compared with it is 295/75R15, which is 0.1" taller (+0.2%). At an indicated 60 mph you would be doing 60.1 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 315/70R15 | |
|---|---|---|---|---|---|
| 295/75R15 | 32.4" | 11.6" | 8.7" | +0.2% | |
| 305/70R15 | 31.8" | 12.0" | 8.4" | −1.7% | |
| 33x12.50R15 | 33.0" | 12.5" | 9.0" | +2.0% | |
| 295/70R15 | 31.3" | 11.6" | 8.1" | −3.4% | |
| 315/75R15 | 33.6" | 12.4" | 9.3" | +3.8% | |
| 325/60R15 | 30.4" | 12.8" | 7.7" | −6.2% | |
| 295/65R15 | 30.1" | 11.6" | 7.5" | −7.0% | |
| 315/60R15 | 29.9" | 12.4" | 7.4" | −7.7% | |
| 35x12.50R15 | 35.0" | 12.5" | 10.0" | +8.2% | |
| 295/60R15 | 28.9" | 11.6" | 7.0" | −10.6% |
Sizes within 2% of 32.4" on 16" or 17" wheels.
| Size | Diameter | Width | Sidewall | vs 315/70R15 | |
|---|---|---|---|---|---|
| 245/85R16 | 32.4" | 9.6" | 8.2" | +0.1% | |
| 245/80R17 | 32.4" | 9.6" | 7.7" | +0.2% | |
| 295/70R16 | 32.3" | 11.6" | 8.1" | −0.3% | |
| 275/75R16 | 32.2" | 10.8" | 8.1" | −0.4% | |
| 275/70R17 | 32.2" | 10.8" | 7.6" | −0.6% | |
| 305/65R17 | 32.6" | 12.0" | 7.8" | +0.8% |
Actual speed when the speedometer is calibrated for 315/70R15.
| Speedometer shows | on 295/75R15 | on 305/70R15 | on 33x12.50R15 |
|---|---|---|---|
| 30 mph | 30.1 mph | 29.5 mph | 30.6 mph |
| 45 mph | 45.1 mph | 44.2 mph | 45.9 mph |
| 60 mph | 60.1 mph | 59.0 mph | 61.2 mph |
| 70 mph | 70.1 mph | 68.8 mph | 71.4 mph |
32.4 inches (822 mm). The sidewall is 8.7 inches.
12.4 inches (315 mm) section width, measured sidewall to sidewall.
About 32.4x12.4R15; the closest common flotation size is 32x11.50R15 at 32.0".
295/75R15 is +0.2% in diameter, within the common 3% guideline. It is 0.8" narrower.