Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 325/40-18 | 38/12.5-18 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 28.24 (717.2) | 38.03 (966) | 9.8 (248.8) 34.7% |
| Width inches (mm) | 12.8 (325) | 12.52 (318) | -0.28 (-7) -2.2% |
| Circum. inches (mm) | 88.71 (2253.15) | 119.48 (3034.78) | 30.77 (781.63) 34.7% |
| Sidewall Height inches (mm) | 5.12 (130) | 10.02 (254.4) | 4.9 (124.4) 95.7% |
| Revolutions per mile (km) | 714.26 (443.82) | 530.3 (329.51) | -183.96 (-114.31) -25.8% |
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 26.94 mph (43.35 km/h) |
| 25 mph (40.23 km/h) | 33.67 mph (54.19 km/h) |
| 30 mph (48.28 km/h) | 40.41 mph (65.03 km/h) |
| 35 mph (56.33 km/h) | 47.14 mph (75.87 km/h) |
| 40 mph (64.37 km/h) | 53.88 mph (86.71 km/h) |
| 45 mph (72.42 km/h) | 60.61 mph (97.54 km/h) |
| 50 mph (80.47 km/h) | 67.35 mph (108.38 km/h) |
| 55 mph (88.51 km/h) | 74.08 mph (119.22 km/h) |
| 60 mph (96.56 km/h) | 80.81 mph (130.06 km/h) |
| 65 mph (104.61 km/h) | 87.55 mph (140.9 km/h) |
| 70 mph (112.65 km/h) | 94.28 mph (151.73 km/h) |
| 75 mph (120.7 km/h) | 101.02 mph (162.57 km/h) |
| 80 mph (128.75 km/h) | 107.75 mph (173.41 km/h) |
| 85 mph (136.79 km/h) | 114.49 mph (184.25 km/h) |
| 90 mph (144.84 km/h) | 121.22 mph (195.09 km/h) |
| 95 mph (152.89 km/h) | 127.96 mph (205.93 km/h) |
| 100 mph (160.93 km/h) | 134.69 mph (216.76 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1350 | 1568 | 1688 | 1763 | 1843 | 1901 | 1964 | 2039 | 2142 | 2245 | 2360 | 2452 | 2619 | 2802 | 2946 | 3038 | 3090 | 3279 | 3543 | 4117 |
Better Fuel Economy Factory Ratios Increased Power
