Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 38/15.5-20 | 40/15.5-20 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 37.99 (965.04) | 40.17 (1020.2) | 2.17 (55.16) 5.7% |
| Width inches (mm) | 15.51 (394) | 15.51 (394) | 0 (0) 0% |
| Circum. inches (mm) | 119.36 (3031.76) | 126.18 (3205.05) | 6.82 (173.29) 5.7% |
| Sidewall Height inches (mm) | 9 (228.52) | 10.08 (256.1) | 1.09 (27.58) 12.1% |
| Revolutions per mile (km) | 530.83 (329.84) | 502.13 (312.01) | -28.7 (-17.83) -5.4% |
40/15.5-20 Tires
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 21.14 mph (34.03 km/h) |
| 25 mph (40.23 km/h) | 26.43 mph (42.53 km/h) |
| 30 mph (48.28 km/h) | 31.71 mph (51.04 km/h) |
| 35 mph (56.33 km/h) | 37 mph (59.55 km/h) |
| 40 mph (64.37 km/h) | 42.29 mph (68.05 km/h) |
| 45 mph (72.42 km/h) | 47.57 mph (76.56 km/h) |
| 50 mph (80.47 km/h) | 52.86 mph (85.07 km/h) |
| 55 mph (88.51 km/h) | 58.14 mph (93.57 km/h) |
| 60 mph (96.56 km/h) | 63.43 mph (102.08 km/h) |
| 65 mph (104.61 km/h) | 68.72 mph (110.59 km/h) |
| 70 mph (112.65 km/h) | 74 mph (119.09 km/h) |
| 75 mph (120.7 km/h) | 79.29 mph (127.6 km/h) |
| 80 mph (128.75 km/h) | 84.57 mph (136.11 km/h) |
| 85 mph (136.79 km/h) | 89.86 mph (144.61 km/h) |
| 90 mph (144.84 km/h) | 95.14 mph (153.12 km/h) |
| 95 mph (152.89 km/h) | 100.43 mph (161.63 km/h) |
| 100 mph (160.93 km/h) | 105.72 mph (170.13 km/h) |
| 2.35 | 2.73 | 2.94 | 3.07 | 3.21 | 3.31 | 3.42 | 3.55 | 3.73 | 3.91 | 4.11 | 4.27 | 4.56 | 4.88 | 5.13 | 5.29 | 5.38 | 5.71 | 6.17 | 7.17 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1278 | 1484 | 1599 | 1669 | 1745 | 1800 | 1860 | 1930 | 2028 | 2126 | 2235 | 2322 | 2480 | 2654 | 2789 | 2876 | 2925 | 3105 | 3355 | 3899 |
Better Fuel Economy Factory Ratios Increased Power
