27.4" tall, 12.4" wide, 6.2" sidewall
A 315/50R15 tire is 27.4 inches (696 mm) tall and 12.4 inches wide. The sidewall is 50% of the width, 6.2 inches, on a 15-inch wheel, and the tire turns about 736 times per mile.
In flotation terms that is about 27.4x12.4R15. People often call it a 27-inch tire.
The size most often compared with it is 295/55R15, which is 0.4" taller (+1.4%). At an indicated 60 mph you would be doing 60.8 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 315/50R15 | |
|---|---|---|---|---|---|
| 295/55R15 | 27.8" | 11.6" | 6.4" | +1.4% | |
| 305/50R15 | 27.0" | 12.0" | 6.0" | −1.4% | |
| 325/50R15 | 27.8" | 12.8" | 6.4" | +1.4% | |
| 295/50R15 | 26.6" | 11.6" | 5.8" | −2.9% | |
| 295/60R15 | 28.9" | 11.6" | 7.0" | +5.6% | |
| 315/60R15 | 29.9" | 12.4" | 7.4" | +9.1% | |
| 325/60R15 | 30.4" | 12.8" | 7.7" | +10.8% |
Sizes within 2% of 27.4" on 17" or 14" wheels.
| Size | Diameter | Width | Sidewall | vs 315/50R15 | |
|---|---|---|---|---|---|
| 265/50R17 | 27.4" | 10.4" | 5.2" | +0.1% | |
| 205/65R17 | 27.5" | 8.1" | 5.2" | +0.3% | |
| 245/55R17 | 27.6" | 9.6" | 5.3" | +0.8% | |
| 285/45R17 | 27.1" | 11.2" | 5.0" | −1.1% | |
| 255/65R14 | 27.1" | 10.0" | 6.5" | −1.3% | |
| 275/50R17 | 27.8" | 10.8" | 5.4" | +1.6% |
Actual speed when the speedometer is calibrated for 315/50R15.
| Speedometer shows | on 295/55R15 | on 305/50R15 | on 325/50R15 |
|---|---|---|---|
| 30 mph | 30.4 mph | 29.6 mph | 30.4 mph |
| 45 mph | 45.6 mph | 44.4 mph | 45.6 mph |
| 60 mph | 60.8 mph | 59.1 mph | 60.9 mph |
| 70 mph | 71.0 mph | 69.0 mph | 71.0 mph |
27.4 inches (696 mm). The sidewall is 6.2 inches.
12.4 inches (315 mm) section width, measured sidewall to sidewall.
About 27.4x12.4R15.
295/55R15 is +1.4% in diameter, within the common 3% guideline. It is 0.8" narrower.