38x12.50R15 tire size
38x12.50R15 is a flotation (inch) size: 38.0" tall, 12.5" wide, on a 15" rim — about a 320/90R15. The sidewall is 11.5" and the tire turns 531 times per mile.
38x12.50R15 specs
| Overall diameter (height) | 38.00" · 965 mm |
|---|---|
| Section width | 12.50" · 318 mm |
| Sidewall height | 11.50" · 292 mm (92% of width) |
| Rim diameter | 15" |
| Circumference | 119.38" · 3.032 m |
| Revolutions per mile | 531 (330 per km) |
| Closest metric size | 320/90R15 |
Equivalent sizes on a 15" 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 | |
|---|---|---|---|---|---|
| 37x12.50R15 | 37.00" | -2.63% | 0 mm | 58.4 mph | calculate → |
| 38x15.50R15 | 38.00" | 0.00% | +76 mm | 60.0 mph | calculate → |
| 38.5x14.50R15 | 38.50" | +1.32% | +50 mm | 60.8 mph | calculate → |
| 37x14.50R15 | 37.00" | -2.63% | +50 mm | 58.4 mph | calculate → |
| 39.5x13.50R15 | 39.50" | +3.95% | +25 mm | 62.4 mph | calculate → |
| 38x13.00R15 | 38.00" | 0.00% | +12 mm | 60.0 mph | calculate → |
| 38.5x11.00R15 | 38.50" | +1.32% | -39 mm | 60.8 mph | calculate → |
| 38.5x13.50R15 | 38.50" | +1.32% | +25 mm | 60.8 mph | calculate → |
| 38.5x15.00R15 | 38.50" | +1.32% | +63 mm | 60.8 mph | calculate → |
| 38.5x16.00R15 | 38.50" | +1.32% | +88 mm | 60.8 mph | calculate → |
| 37x13.50R15 | 37.00" | -2.63% | +25 mm | 58.4 mph | calculate → |
| 37x13.00R15 | 37.00" | -2.63% | +12 mm | 58.4 mph | calculate → |
| 37x14.00R15 | 37.00" | -2.63% | +38 mm | 58.4 mph | calculate → |
| 39.5x15.00R15 | 39.50" | +3.95% | +63 mm | 62.4 mph | calculate → |
| 39.5x18.00R15 | 39.50" | +3.95% | +139 mm | 62.4 mph | calculate → |
| 38x14.50R15 | 38.00" | 0.00% | +50 mm | 60.0 mph | calculate → |
| 39x13.50R15 | 39.00" | +2.63% | +25 mm | 61.6 mph | calculate → |
Plus / minus sizing: 14" and 16" rims
Same overall height on a different rim. Check wheel width and clearance before switching.
| Size | Diameter | Difference | Width | Speedo at 60 | |
|---|---|---|---|---|---|
| 38x13.00R16 | 38.00" | 0.00% | +12 mm | 60.0 mph | calculate → |
| 38x15.50R16 | 38.00" | 0.00% | +76 mm | 60.0 mph | calculate → |
| 38x14.50R16 | 38.00" | 0.00% | +50 mm | 60.0 mph | calculate → |
| 395/70R16 | 37.77" | -0.60% | +77 mm | 59.6 mph | calculate → |
Try another size against 38x12.50R15
Questions
What size is 38x12.50R15 in inches?
38x12.50R15 is about 38.0" tall and 12.5" wide on a 15-inch rim — roughly a 320/90R15 in inch sizing.
What does 38x12.50R15 mean?
38" overall diameter, 12.50" section width, radial, 15" rim.
What tire sizes are equivalent to 38x12.50R15?
On the same 15" rim, within 3% of the diameter: 38x13.00R15 (0.00%), 38x14.50R15 (0.00%), 38x15.50R15 (0.00%), 38.5x11.00R15 (+1.32%), 38.5x13.50R15 (+1.32%), 38.5x14.50R15 (+1.32%).
How many revolutions per mile does a 38x12.50R15 tire make?
About 531 revolutions per mile (circumference 119.4").
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.