32.4" tall, 12.4" wide, 6.2" sidewall
A 315/50R20 tire is 32.4 inches (823 mm) tall and 12.4 inches wide. The sidewall is 50% of the width, 6.2 inches, on a 20-inch wheel, and the tire turns about 622 times per mile.
In flotation terms that is about 32.4x12.4R20, closest to the common 33x12.50R20 (33.0"). People often call it a 32-inch tire.
The size most often compared with it is 295/55R20, which is 0.4" taller (+1.2%). At an indicated 60 mph you would be doing 60.7 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 315/50R20 | |
|---|---|---|---|---|---|
| 295/55R20 | 32.8" | 11.6" | 6.4" | +1.2% | |
| 305/50R20 | 32.0" | 12.0" | 6.0" | −1.2% | |
| 325/50R20 | 32.8" | 12.8" | 6.4" | +1.2% | |
| 33x12.50R20 | 33.0" | 12.5" | 6.5" | +1.8% | |
| 295/50R20 | 31.6" | 11.6" | 5.8" | −2.4% | |
| 305/55R20 | 33.2" | 12.0" | 6.6" | +2.5% | |
| 315/45R20 | 31.2" | 12.4" | 5.6" | −3.8% | |
| 315/55R20 | 33.6" | 12.4" | 6.8" | +3.8% | |
| 295/60R20 | 33.9" | 11.6" | 7.0" | +4.7% | |
| 305/45R20 | 30.8" | 12.0" | 5.4" | −4.9% |
Sizes within 2% of 32.4" on 18" or 22" or 19" wheels.
| Size | Diameter | Width | Sidewall | vs 315/50R20 | |
|---|---|---|---|---|---|
| 305/60R18 | 32.4" | 12.0" | 7.2" | +0.0% | |
| 265/50R22 | 32.4" | 10.4" | 5.2" | +0.1% | |
| 295/45R22 | 32.5" | 11.6" | 5.2" | +0.2% | |
| 245/75R18 | 32.5" | 9.6" | 7.2" | +0.2% | |
| 245/70R19 | 32.5" | 9.6" | 6.8" | +0.3% | |
| 225/75R19 | 32.3" | 8.9" | 6.6" | −0.4% |
Actual speed when the speedometer is calibrated for 315/50R20.
| Speedometer shows | on 295/55R20 | on 305/50R20 | on 325/50R20 |
|---|---|---|---|
| 30 mph | 30.3 mph | 29.6 mph | 30.4 mph |
| 45 mph | 45.5 mph | 44.5 mph | 45.5 mph |
| 60 mph | 60.7 mph | 59.3 mph | 60.7 mph |
| 70 mph | 70.8 mph | 69.1 mph | 70.9 mph |
32.4 inches (823 mm). The sidewall is 6.2 inches.
12.4 inches (315 mm) section width, measured sidewall to sidewall.
About 32.4x12.4R20; the closest common flotation size is 33x12.50R20 at 33.0".
295/55R20 is +1.2% in diameter, within the common 3% guideline. It is 0.8" narrower.