37.0" tall, 12.5" wide on a 20" wheel
A 37x12.50R20 tire is 37.0 inches tall and 12.5 inches wide and mounts on a 20-inch wheel, which leaves a 8.5-inch sidewall. It turns about 545 times per mile.
The size most often compared with it is 35x12.50R20, which is 2.0" shorter (−5.4%). At an indicated 60 mph you would be doing 56.8 mph on it, more than the 3% change many shops use as a limit.
| 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 37x12.50R20 | |
|---|---|---|---|---|---|
| 315/65R20 | 36.1" | 12.4" | 8.1" | −2.4% | |
| 305/65R20 | 35.6" | 12.0" | 7.8" | −3.8% | |
| 325/60R20 | 35.4" | 12.8" | 7.7" | −4.4% | |
| 35x12.50R20 | 35.0" | 12.5" | 7.5" | −5.4% | compare |
| 315/60R20 | 34.9" | 12.4" | 7.4" | −5.7% | |
| 305/60R20 | 34.4" | 12.0" | 7.2" | −7.0% |
Sizes within 2% of 37.0" on 18" or 22" wheels.
| Size | Diameter | Width | Sidewall | vs 37x12.50R20 | |
|---|---|---|---|---|---|
| 37x12.50R18 | 37.0" | 12.5" | 9.5" | ±0.0% | |
| 37x12.50R22 | 37.0" | 12.5" | 7.5" | ±0.0% | |
| 37x13.50R18 | 37.0" | 13.5" | 9.5" | ±0.0% | |
| 37x13.50R22 | 37.0" | 13.5" | 7.5" | ±0.0% | |
| 275/85R18 | 36.4" | 10.8" | 9.2" | −1.6% |
Actual speed when the speedometer is calibrated for 37x12.50R20.
| Speedometer shows | on 35x12.50R20 | on 315/65R20 | on 305/65R20 |
|---|---|---|---|
| 30 mph | 28.4 mph | 29.3 mph | 28.9 mph |
| 45 mph | 42.6 mph | 43.9 mph | 43.3 mph |
| 60 mph | 56.8 mph | 58.6 mph | 57.7 mph |
| 70 mph | 66.2 mph | 68.3 mph | 67.4 mph |
37.0 inches (940 mm), with a 8.5-inch sidewall on a 20-inch wheel.
There is no common metric size within half an inch of 37.0".
About 545, or 339 per kilometer.