31x9.50R15 tire size
31x9.50R15 is a flotation (inch) size: 31.0" tall, 9.5" wide, on a 15" rim — about a 240/85R15. The sidewall is 8.0" and the tire turns 651 times per mile.
31x9.50R15 specs
| Overall diameter (height) | 31.00" · 787 mm |
|---|---|
| Section width | 9.50" · 241 mm |
| Sidewall height | 8.00" · 203 mm (84% of width) |
| Rim diameter | 15" |
| Circumference | 97.39" · 2.474 m |
| Revolutions per mile | 651 (404 per km) |
| Closest metric size | 240/85R15 |
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 | |
|---|---|---|---|---|---|
| 31x10.50R15 common | 31.00" | 0.00% | +26 mm | 60.0 mph | calculate → |
| 30x9.50R15 | 30.00" | -3.23% | 0 mm | 58.1 mph | calculate → |
| 32x11.50R15 | 32.00" | +3.23% | +51 mm | 61.9 mph | calculate → |
| 265/75R15 | 30.65" | -1.13% | +24 mm | 59.3 mph | calculate → |
| 265/70R15 | 29.61" | -4.50% | +24 mm | 57.3 mph | calculate → |
| 31x12.50R15 | 31.00" | 0.00% | +77 mm | 60.0 mph | calculate → |
| 295/65R15 | 30.10" | -2.91% | +54 mm | 58.3 mph | calculate → |
| 30x11.50R15 | 30.00" | -3.23% | +51 mm | 58.1 mph | calculate → |
| 31x11.50R15 | 31.00" | 0.00% | +51 mm | 60.0 mph | calculate → |
| 31x11.00R15 | 31.00" | 0.00% | +38 mm | 60.0 mph | calculate → |
| 31x13.50R15 | 31.00" | 0.00% | +102 mm | 60.0 mph | calculate → |
| 31x13.00R15 | 31.00" | 0.00% | +89 mm | 60.0 mph | calculate → |
| 31x16.50R15 | 31.00" | 0.00% | +178 mm | 60.0 mph | calculate → |
| 31x16.00R15 | 31.00" | 0.00% | +165 mm | 60.0 mph | calculate → |
| 31x18.00R15 | 31.00" | 0.00% | +216 mm | 60.0 mph | calculate → |
| 255/75R15 | 30.06" | -3.04% | +14 mm | 58.2 mph | calculate → |
| 30x10.50R15 | 30.00" | -3.23% | +26 mm | 58.1 mph | calculate → |
| 30x10.00R15 | 30.00" | -3.23% | +13 mm | 58.1 mph | calculate → |
| 30x12.00R15 | 30.00" | -3.23% | +64 mm | 58.1 mph | calculate → |
| 30x9.00R15 | 30.00" | -3.23% | -12 mm | 58.1 mph | calculate → |
| 32x10.50R15 | 32.00" | +3.23% | +26 mm | 61.9 mph | calculate → |
| 32x10.00R15 | 32.00" | +3.23% | +13 mm | 61.9 mph | calculate → |
| 32x14.00R15 | 32.00" | +3.23% | +115 mm | 61.9 mph | calculate → |
| 32x16.00R15 | 32.00" | +3.23% | +165 mm | 61.9 mph | calculate → |
| 32x17.50R15 | 32.00" | +3.23% | +204 mm | 61.9 mph | calculate → |
| 32x9.50R15 | 32.00" | +3.23% | 0 mm | 61.9 mph | calculate → |
| 29.5x10.50R15 | 29.50" | -4.84% | +26 mm | 57.1 mph | calculate → |
| 29.5x11.50R15 | 29.50" | -4.84% | +51 mm | 57.1 mph | calculate → |
| 29.5x13.50R15 | 29.50" | -4.84% | +102 mm | 57.1 mph | calculate → |
| 29.5x9.00R15 | 29.50" | -4.84% | -12 mm | 57.1 mph | calculate → |
| 31x14.50R15 | 31.00" | 0.00% | +127 mm | 60.0 mph | calculate → |
| 31x18.50R15 | 31.00" | 0.00% | +229 mm | 60.0 mph | calculate → |
| 30x12.50R15 | 30.00" | -3.23% | +77 mm | 58.1 mph | calculate → |
| 30x13.50R15 | 30.00" | -3.23% | +102 mm | 58.1 mph | calculate → |
| 30x7.00R15 | 30.00" | -3.23% | -63 mm | 58.1 mph | calculate → |
| 32x18.50R15 | 32.00" | +3.23% | +229 mm | 61.9 mph | calculate → |
| 315/60R15 | 29.88" | -3.61% | +74 mm | 57.8 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 | |
|---|---|---|---|---|---|
| 275/70R16 | 31.16" | +0.51% | +34 mm | 60.3 mph | calculate → |
| 235/80R16 | 30.80" | -0.64% | -6 mm | 59.6 mph | calculate → |
| 31x12.50R16 | 31.00" | 0.00% | +77 mm | 60.0 mph | calculate → |
| 31x10.50R16 | 31.00" | 0.00% | +26 mm | 60.0 mph | calculate → |
| 31x11.50R16 | 31.00" | 0.00% | +51 mm | 60.0 mph | calculate → |
| 31x11.00R16 | 31.00" | 0.00% | +38 mm | 60.0 mph | calculate → |
| 225/85R16 | 31.06" | +0.19% | -16 mm | 60.1 mph | calculate → |
Try another size against 31x9.50R15
Questions
What size is 31x9.50R15 in inches?
31x9.50R15 is about 31.0" tall and 9.5" wide on a 15-inch rim — roughly a 240/85R15 in inch sizing.
What does 31x9.50R15 mean?
31" overall diameter, 9.50" section width, radial, 15" rim.
What tire sizes are equivalent to 31x9.50R15?
On the same 15" rim, within 3% of the diameter: 31x10.50R15 (0.00%), 31x11.50R15 (0.00%), 31x11.00R15 (0.00%), 31x12.50R15 (0.00%), 31x13.50R15 (0.00%), 31x13.00R15 (0.00%).
How many revolutions per mile does a 31x9.50R15 tire make?
About 651 revolutions per mile (circumference 97.4").
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.