Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 325/65-18 | 37/12.5-18 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 34.63 (879.7) | 37.03 (940.56) | 2.4 (60.86) 6.9% |
| Width inches (mm) | 12.8 (325) | 12.52 (318) | -0.28 (-7) -2.2% |
| Circum. inches (mm) | 108.81 (2763.66) | 116.33 (2954.86) | 7.53 (191.2) 6.9% |
| Sidewall Height inches (mm) | 8.32 (211.25) | 9.51 (241.68) | 1.2 (30.43) 14.4% |
| Revolutions per mile (km) | 582.32 (361.84) | 544.64 (338.43) | -37.68 (-23.41) -6.5% |
37/12.5-18 Tires
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 21.38 mph (34.41 km/h) |
| 25 mph (40.23 km/h) | 26.73 mph (43.02 km/h) |
| 30 mph (48.28 km/h) | 32.08 mph (51.62 km/h) |
| 35 mph (56.33 km/h) | 37.42 mph (60.22 km/h) |
| 40 mph (64.37 km/h) | 42.77 mph (68.83 km/h) |
| 45 mph (72.42 km/h) | 48.11 mph (77.43 km/h) |
| 50 mph (80.47 km/h) | 53.46 mph (86.03 km/h) |
| 55 mph (88.51 km/h) | 58.81 mph (94.64 km/h) |
| 60 mph (96.56 km/h) | 64.15 mph (103.24 km/h) |
| 65 mph (104.61 km/h) | 69.5 mph (111.84 km/h) |
| 70 mph (112.65 km/h) | 74.84 mph (120.45 km/h) |
| 75 mph (120.7 km/h) | 80.19 mph (129.05 km/h) |
| 80 mph (128.75 km/h) | 85.53 mph (137.65 km/h) |
| 85 mph (136.79 km/h) | 90.88 mph (146.26 km/h) |
| 90 mph (144.84 km/h) | 96.23 mph (154.86 km/h) |
| 95 mph (152.89 km/h) | 101.57 mph (163.47 km/h) |
| 100 mph (160.93 km/h) | 106.92 mph (172.07 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1386 | 1610 | 1734 | 1811 | 1893 | 1952 | 2017 | 2094 | 2200 | 2306 | 2424 | 2518 | 2689 | 2878 | 3026 | 3120 | 3173 | 3368 | 3639 | 4229 |
Better Fuel Economy Factory Ratios Increased Power
