34.4" tall, 12.0" wide, 7.2" sidewall
A 305/60R20 tire is 34.4 inches (874 mm) tall and 12.0 inches wide. The sidewall is 60% of the width, 7.2 inches, on a 20-inch wheel, and the tire turns about 586 times per mile.
In flotation terms that is about 34.4x12.0R20, closest to the common 35x11.50R20 (35.0"). People often call it a 34-inch tire.
The size most often compared with it is 285/65R20, which is 0.2" taller (+0.5%). At an indicated 60 mph you would be doing 60.3 mph on it.
| Current | New | Difference |
|---|
| Shows | Actual speed |
|---|
Same 20" wheel, within 20 mm of width and 10 points of aspect ratio.
| Size | Diameter | Width | Sidewall | vs 305/60R20 | |
|---|---|---|---|---|---|
| 285/65R20 | 34.6" | 11.2" | 7.3" | +0.5% | |
| 325/55R20 | 34.1" | 12.8" | 7.0" | −1.0% | |
| 295/60R20 | 33.9" | 11.6" | 7.0" | −1.4% | |
| 315/60R20 | 34.9" | 12.4" | 7.4" | +1.4% | |
| 35x11.50R20 | 35.0" | 11.5" | 7.5" | +1.7% | |
| 35x12.50R20 | 35.0" | 12.5" | 7.5" | +1.7% | |
| 295/65R20 | 35.1" | 11.6" | 7.5" | +2.0% | |
| 315/55R20 | 33.6" | 12.4" | 6.8" | −2.2% | |
| 325/60R20 | 35.4" | 12.8" | 7.7" | +2.7% | |
| 285/60R20 | 33.5" | 11.2" | 6.7" | −2.7% |
Sizes within 2% of 34.4" on 22" or 18" wheels.
| Size | Diameter | Width | Sidewall | vs 305/60R20 | |
|---|---|---|---|---|---|
| 225/70R22 | 34.4" | 8.9" | 6.2" | −0.0% | |
| 315/50R22 | 34.4" | 12.4" | 6.2" | −0.0% | |
| 285/55R22 | 34.3" | 11.2" | 6.2" | −0.2% | |
| 265/60R22 | 34.5" | 10.4" | 6.3" | +0.3% | |
| 295/70R18 | 34.3" | 11.6" | 8.1" | −0.4% | |
| 275/75R18 | 34.2" | 10.8" | 8.1" | −0.5% |
Actual speed when the speedometer is calibrated for 305/60R20.
| Speedometer shows | on 285/65R20 | on 325/55R20 | on 295/60R20 |
|---|---|---|---|
| 30 mph | 30.2 mph | 29.7 mph | 29.6 mph |
| 45 mph | 45.2 mph | 44.6 mph | 44.4 mph |
| 60 mph | 60.3 mph | 59.4 mph | 59.2 mph |
| 70 mph | 70.4 mph | 69.3 mph | 69.0 mph |
34.4 inches (874 mm). The sidewall is 7.2 inches.
12.0 inches (305 mm) section width, measured sidewall to sidewall.
About 34.4x12.0R20; the closest common flotation size is 35x11.50R20 at 35.0".
285/65R20 is +0.5% in diameter, within the common 3% guideline. It is 0.8" narrower.