34.9" tall, 12.4" wide, 7.4" sidewall
A 315/60R20 tire is 34.9 inches (886 mm) tall and 12.4 inches wide. The sidewall is 60% of the width, 7.4 inches, on a 20-inch wheel, and the tire turns about 578 times per mile.
In flotation terms that is about 34.9x12.4R20, closest to the common 35x11.50R20 (35.0"). People often call it a 35-inch tire.
The size most often compared with it is 35x12.50R20, which is 0.1" taller (+0.3%). At an indicated 60 mph you would be doing 60.2 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 315/60R20 | |
|---|---|---|---|---|---|
| 35x12.50R20 | 35.0" | 12.5" | 7.5" | +0.3% | |
| 295/65R20 | 35.1" | 11.6" | 7.5" | +0.6% | |
| 305/60R20 | 34.4" | 12.0" | 7.2" | −1.4% | |
| 325/60R20 | 35.4" | 12.8" | 7.7" | +1.4% | |
| 305/65R20 | 35.6" | 12.0" | 7.8" | +2.1% | |
| 325/55R20 | 34.1" | 12.8" | 7.0" | −2.3% | |
| 295/60R20 | 33.9" | 11.6" | 7.0" | −2.7% | |
| 315/55R20 | 33.6" | 12.4" | 6.8" | −3.6% | |
| 315/65R20 | 36.1" | 12.4" | 8.1" | +3.6% | |
| 295/70R20 | 36.3" | 11.6" | 8.1" | +4.0% |
Sizes within 2% of 34.9" on 18" or 22" wheels.
| Size | Diameter | Width | Sidewall | vs 315/60R20 | |
|---|---|---|---|---|---|
| 285/75R18 | 34.8" | 11.2" | 8.4" | −0.1% | |
| 305/70R18 | 34.8" | 12.0" | 8.4" | −0.2% | |
| 325/50R22 | 34.8" | 12.8" | 6.4" | −0.2% | |
| 295/55R22 | 34.8" | 11.6" | 6.4" | −0.3% | |
| 275/60R22 | 35.0" | 10.8" | 6.5" | +0.3% | |
| 35x12.50R18 | 35.0" | 12.5" | 8.5" | +0.3% |
Actual speed when the speedometer is calibrated for 315/60R20.
| Speedometer shows | on 35x12.50R20 | on 295/65R20 | on 305/60R20 |
|---|---|---|---|
| 30 mph | 30.1 mph | 30.2 mph | 29.6 mph |
| 45 mph | 45.2 mph | 45.3 mph | 44.4 mph |
| 60 mph | 60.2 mph | 60.4 mph | 59.2 mph |
| 70 mph | 70.2 mph | 70.4 mph | 69.1 mph |
34.9 inches (886 mm). The sidewall is 7.4 inches.
12.4 inches (315 mm) section width, measured sidewall to sidewall.
About 34.9x12.4R20; the closest common flotation size is 35x11.50R20 at 35.0".
35x12.50R20 is +0.3% in diameter, within the common 3% guideline. It is 0.1" wider.