38.5x13.50R20 tire size
38.5x13.50R20 is a flotation (inch) size: 38.5" tall, 13.5" wide, on a 20" rim — about a 340/70R20. The sidewall is 9.3" and the tire turns 524 times per mile.
38.5x13.50R20 specs
| Overall diameter (height) | 38.50" · 978 mm |
|---|---|
| Section width | 13.50" · 343 mm |
| Sidewall height | 9.25" · 235 mm (69% of width) |
| Rim diameter | 20" |
| Circumference | 120.95" · 3.072 m |
| Revolutions per mile | 524 (326 per km) |
| Closest metric size | 340/70R20 |
Equivalent sizes on a 20" rim
Sizes within ±5% of the overall diameter. Green rows are inside the usual ±3% limit for keeping the speedometer, ABS and gearing right; red rows are bigger changes that need clearance checks.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 37x12.50R20 | 37.00" | -3.90% | -25 mm | 57.7 mph | calculate → |
| 37x13.50R20 | 37.00" | -3.90% | 0 mm | 57.7 mph | calculate → |
| 38x13.50R20 | 38.00" | -1.30% | 0 mm | 59.2 mph | calculate → |
| 38x15.50R20 | 38.00" | -1.30% | +51 mm | 59.2 mph | calculate → |
| 37x11.50R20 | 37.00" | -3.90% | -51 mm | 57.7 mph | calculate → |
| 40x15.50R20 | 40.00" | +3.90% | +51 mm | 62.3 mph | calculate → |
| 40x14.50R20 | 40.00" | +3.90% | +25 mm | 62.3 mph | calculate → |
| 38x14.50R20 | 38.00" | -1.30% | +25 mm | 59.2 mph | calculate → |
| 39.5x13.50R20 | 39.50" | +2.60% | 0 mm | 61.6 mph | calculate → |
| 40x13.50R20 | 40.00" | +3.90% | 0 mm | 62.3 mph | calculate → |
| 38.5x14.50R20 | 38.50" | 0.00% | +25 mm | 60.0 mph | calculate → |
| 395/60R20 | 38.66" | +0.42% | +52 mm | 60.3 mph | calculate → |
| 38x11.50R20 | 38.00" | -1.30% | -51 mm | 59.2 mph | calculate → |
| 37x14.50R20 | 37.00" | -3.90% | +25 mm | 57.7 mph | calculate → |
| 39x13.50R20 | 39.00" | +1.30% | 0 mm | 60.8 mph | calculate → |
| 39.5x15.00R20 | 39.50" | +2.60% | +38 mm | 61.6 mph | calculate → |
| 355/60R20 | 36.77" | -4.49% | +12 mm | 57.3 mph | calculate → |
Try another size against 38.5x13.50R20
Questions
What size is 38.5x13.50R20 in inches?
38.5x13.50R20 is about 38.5" tall and 13.5" wide on a 20-inch rim — roughly a 340/70R20 in inch sizing.
What does 38.5x13.50R20 mean?
38.5" overall diameter, 13.50" section width, radial, 20" rim.
What tire sizes are equivalent to 38.5x13.50R20?
On the same 20" rim, within 3% of the diameter: 38.5x14.50R20 (0.00%), 395/60R20 (+0.42%), 38x11.50R20 (-1.30%), 38x13.50R20 (-1.30%), 38x14.50R20 (-1.30%), 38x15.50R20 (-1.30%).
How many revolutions per mile does a 38.5x13.50R20 tire make?
About 524 revolutions per mile (circumference 121.0").
How these numbers are computed
Diameter = rim + 2 × sidewall, sidewall = width × aspect ÷ 100, circumference = π × diameter, revolutions per mile = 63,360 ÷ circumference. Real tires differ by brand by a few tenths of an inch. Last reviewed October 14, 2026.