30.2" tall, 12.0" wide, 6.6" sidewall
A 305/55R17 tire is 30.2 inches (767 mm) tall and 12.0 inches wide. The sidewall is 55% of the width, 6.6 inches, on a 17-inch wheel, and the tire turns about 668 times per mile.
In flotation terms that is about 30.2x12.0R17. People often call it a 30-inch tire.
The size most often compared with it is 285/60R17, which is 0.3" taller (+0.8%). At an indicated 60 mph you would be doing 60.5 mph on it.
| Current | New | Difference |
|---|
| Shows | Actual speed |
|---|
Same 17" wheel, within 20 mm of width and 10 points of aspect ratio.
| Size | Diameter | Width | Sidewall | vs 305/55R17 | |
|---|---|---|---|---|---|
| 285/60R17 | 30.5" | 11.2" | 6.7" | +0.8% | |
| 315/55R17 | 30.6" | 12.4" | 6.8" | +1.4% | |
| 315/50R17 | 29.4" | 12.4" | 6.2" | −2.7% | |
| 285/55R17 | 29.3" | 11.2" | 6.2" | −2.9% | |
| 305/60R17 | 31.4" | 12.0" | 7.2" | +4.0% | |
| 285/65R17 | 31.6" | 11.2" | 7.3" | +4.6% | |
| 315/60R17 | 31.9" | 12.4" | 7.4" | +5.5% | |
| 325/45R17 | 28.5" | 12.8" | 5.8" | −5.6% | |
| 295/65R17 | 32.1" | 11.6" | 7.5" | +6.3% | |
| 305/65R17 | 32.6" | 12.0" | 7.8" | +7.9% |
Sizes within 2% of 30.2" on 15" or 16" or 18" wheels.
| Size | Diameter | Width | Sidewall | vs 305/55R17 | |
|---|---|---|---|---|---|
| 275/70R15 | 30.2" | 10.8" | 7.6" | −0.2% | |
| 295/65R15 | 30.1" | 11.6" | 7.5" | −0.4% | |
| 275/65R16 | 30.1" | 10.8" | 7.0" | −0.4% | |
| 285/55R18 | 30.3" | 11.2" | 6.2" | +0.4% | |
| 325/60R15 | 30.4" | 12.8" | 7.7" | +0.5% | |
| 255/75R15 | 30.1" | 10.0" | 7.5" | −0.5% |
Actual speed when the speedometer is calibrated for 305/55R17.
| Speedometer shows | on 285/60R17 | on 315/55R17 | on 315/50R17 |
|---|---|---|---|
| 30 mph | 30.3 mph | 30.4 mph | 29.2 mph |
| 45 mph | 45.4 mph | 45.6 mph | 43.8 mph |
| 60 mph | 60.5 mph | 60.9 mph | 58.4 mph |
| 70 mph | 70.6 mph | 71.0 mph | 68.1 mph |
30.2 inches (767 mm). The sidewall is 6.6 inches.
12.0 inches (305 mm) section width, measured sidewall to sidewall.
About 30.2x12.0R17.
285/60R17 is +0.8% in diameter, within the common 3% guideline. It is 0.8" narrower.