29.9" tall, 12.4" wide, 7.4" sidewall
A 315/60R15 tire is 29.9 inches (759 mm) tall and 12.4 inches wide. The sidewall is 60% of the width, 7.4 inches, on a 15-inch wheel, and the tire turns about 675 times per mile.
In flotation terms that is about 29.9x12.4R15, closest to the common 30x9.50R15 (30.0"). People often call it a 30-inch tire.
The size most often compared with it is 295/65R15, which is 0.2" taller (+0.7%). At an indicated 60 mph you would be doing 60.4 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 315/60R15 | |
|---|---|---|---|---|---|
| 295/65R15 | 30.1" | 11.6" | 7.5" | +0.7% | |
| 325/60R15 | 30.4" | 12.8" | 7.7" | +1.6% | |
| 295/60R15 | 28.9" | 11.6" | 7.0" | −3.2% | |
| 295/70R15 | 31.3" | 11.6" | 8.1" | +4.6% | |
| 305/70R15 | 31.8" | 12.0" | 8.4" | +6.5% | |
| 325/50R15 | 27.8" | 12.8" | 6.4" | −7.0% | |
| 295/55R15 | 27.8" | 11.6" | 6.4" | −7.0% | |
| 315/50R15 | 27.4" | 12.4" | 6.2" | −8.3% | |
| 315/70R15 | 32.4" | 12.4" | 8.7" | +8.3% | |
| 305/50R15 | 27.0" | 12.0" | 6.0" | −9.6% |
Sizes within 2% of 29.9" on 16" or 17" or 14" wheels.
| Size | Diameter | Width | Sidewall | vs 315/60R15 | |
|---|---|---|---|---|---|
| 235/75R16 | 29.9" | 9.3" | 6.9" | −0.0% | |
| 235/70R17 | 30.0" | 9.3" | 6.5" | +0.2% | |
| 275/60R17 | 30.0" | 10.8" | 6.5" | +0.4% | |
| 255/65R17 | 30.1" | 10.0" | 6.5" | +0.6% | |
| 255/70R16 | 30.1" | 10.0" | 7.0" | +0.6% | |
| 255/80R14 | 30.1" | 10.0" | 8.0" | +0.6% |
Actual speed when the speedometer is calibrated for 315/60R15.
| Speedometer shows | on 295/65R15 | on 325/60R15 | on 295/60R15 |
|---|---|---|---|
| 30 mph | 30.2 mph | 30.5 mph | 29.1 mph |
| 45 mph | 45.3 mph | 45.7 mph | 43.6 mph |
| 60 mph | 60.4 mph | 60.9 mph | 58.1 mph |
| 70 mph | 70.5 mph | 71.1 mph | 67.8 mph |
29.9 inches (759 mm). The sidewall is 7.4 inches.
12.4 inches (315 mm) section width, measured sidewall to sidewall.
About 29.9x12.4R15; the closest common flotation size is 30x9.50R15 at 30.0".
295/65R15 is +0.7% in diameter, within the common 3% guideline. It is 0.8" narrower.