27.0" tall, 12.0" wide, 6.0" sidewall
A 305/50R15 tire is 27.0 inches (686 mm) tall and 12.0 inches wide. The sidewall is 50% of the width, 6.0 inches, on a 15-inch wheel, and the tire turns about 747 times per mile.
In flotation terms that is about 27.0x12.0R15. People often call it a 27-inch tire.
The size most often compared with it is 295/50R15, which is 0.4" shorter (−1.5%). At an indicated 60 mph you would be doing 59.1 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 305/50R15 | |
|---|---|---|---|---|---|
| 295/50R15 | 26.6" | 11.6" | 5.8" | −1.5% | |
| 315/50R15 | 27.4" | 12.4" | 6.2" | +1.5% | |
| 295/55R15 | 27.8" | 11.6" | 6.4" | +2.8% | |
| 325/50R15 | 27.8" | 12.8" | 6.4" | +2.9% | |
| 285/60R15 | 28.5" | 11.2" | 6.7" | +5.4% | |
| 295/60R15 | 28.9" | 11.6" | 7.0" | +7.1% | |
| 315/60R15 | 29.9" | 12.4" | 7.4" | +10.6% | |
| 325/60R15 | 30.4" | 12.8" | 7.7" | +12.4% |
Sizes within 2% of 27.0" on 14" or 17" wheels.
| Size | Diameter | Width | Sidewall | vs 305/50R15 | |
|---|---|---|---|---|---|
| 255/65R14 | 27.1" | 10.0" | 6.5" | +0.2% | |
| 285/45R17 | 27.1" | 11.2" | 5.0" | +0.3% | |
| 215/75R14 | 26.7" | 8.5" | 6.3" | −1.2% | |
| 205/60R17 | 26.7" | 8.1" | 4.8" | −1.2% | |
| 305/40R17 | 26.6" | 12.0" | 4.8" | −1.5% | |
| 265/50R17 | 27.4" | 10.4" | 5.2" | +1.6% |
Actual speed when the speedometer is calibrated for 305/50R15.
| Speedometer shows | on 295/50R15 | on 315/50R15 | on 295/55R15 |
|---|---|---|---|
| 30 mph | 29.6 mph | 30.4 mph | 30.9 mph |
| 45 mph | 44.3 mph | 45.7 mph | 46.3 mph |
| 60 mph | 59.1 mph | 60.9 mph | 61.7 mph |
| 70 mph | 69.0 mph | 71.0 mph | 72.0 mph |
27.0 inches (686 mm). The sidewall is 6.0 inches.
12.0 inches (305 mm) section width, measured sidewall to sidewall.
About 27.0x12.0R15.
295/50R15 is −1.5% in diameter, within the common 3% guideline. It is 0.4" narrower.