39.5x18.00R15 tire size
39.5x18.00R15 is a flotation (inch) size: 39.5" tall, 18.0" wide, on a 15" rim — about a 460/70R15. The sidewall is 12.3" and the tire turns 511 times per mile.
39.5x18.00R15 specs
| Overall diameter (height) | 39.50" · 1003 mm |
|---|---|
| Section width | 18.00" · 457 mm |
| Sidewall height | 12.25" · 311 mm (68% of width) |
| Rim diameter | 15" |
| Circumference | 124.09" · 3.152 m |
| Revolutions per mile | 511 (317 per km) |
| Closest metric size | 460/70R15 |
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 | |
|---|---|---|---|---|---|
| 38x15.50R15 | 38.00" | -3.80% | -63 mm | 57.7 mph | calculate → |
| 39.5x13.50R15 | 39.50" | 0.00% | -114 mm | 60.0 mph | calculate → |
| 38.5x14.50R15 | 38.50" | -2.53% | -89 mm | 58.5 mph | calculate → |
| 38x12.50R15 | 38.00" | -3.80% | -139 mm | 57.7 mph | calculate → |
| 39.5x15.00R15 | 39.50" | 0.00% | -76 mm | 60.0 mph | calculate → |
| 40x16.00R15 | 40.00" | +1.27% | -51 mm | 60.8 mph | calculate → |
| 38.5x11.00R15 | 38.50" | -2.53% | -178 mm | 58.5 mph | calculate → |
| 38.5x13.50R15 | 38.50" | -2.53% | -114 mm | 58.5 mph | calculate → |
| 38.5x15.00R15 | 38.50" | -2.53% | -76 mm | 58.5 mph | calculate → |
| 38.5x16.00R15 | 38.50" | -2.53% | -51 mm | 58.5 mph | calculate → |
| 38x13.00R15 | 38.00" | -3.80% | -127 mm | 57.7 mph | calculate → |
| 39x13.50R15 | 39.00" | -1.27% | -114 mm | 59.2 mph | calculate → |
| 38x14.50R15 | 38.00" | -3.80% | -89 mm | 57.7 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 | |
|---|---|---|---|---|---|
| 39.5x13.50R16 | 39.50" | 0.00% | -114 mm | 60.0 mph | calculate → |
| 39.5x15.00R16 | 39.50" | 0.00% | -76 mm | 60.0 mph | calculate → |
Try another size against 39.5x18.00R15
Questions
What size is 39.5x18.00R15 in inches?
39.5x18.00R15 is about 39.5" tall and 18.0" wide on a 15-inch rim — roughly a 460/70R15 in inch sizing.
What does 39.5x18.00R15 mean?
39.5" overall diameter, 18.00" section width, radial, 15" rim.
What tire sizes are equivalent to 39.5x18.00R15?
On the same 15" rim, within 3% of the diameter: 39.5x13.50R15 (0.00%), 39.5x15.00R15 (0.00%), 39x13.50R15 (-1.27%), 40x16.00R15 (+1.27%), 38.5x11.00R15 (-2.53%), 38.5x13.50R15 (-2.53%).
How many revolutions per mile does a 39.5x18.00R15 tire make?
About 511 revolutions per mile (circumference 124.1").
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.