Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 120/85-18 | 31/8.5-17.5 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 26.03 (661.2) | 30.94 (785.78) | 4.9 (124.58) 18.8% |
| Width inches (mm) | 4.72 (120) | 8.5 (216) | 3.78 (96) 80% |
| Circum. inches (mm) | 81.78 (2077.22) | 97.19 (2468.6) | 15.41 (391.38) 18.8% |
| Sidewall Height inches (mm) | 4.02 (102) | 6.72 (170.64) | 2.7 (68.64) 67.3% |
| Revolutions per mile (km) | 774.76 (481.41) | 651.93 (405.09) | -122.83 (-76.32) -15.9% |
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 23.77 mph (38.25 km/h) |
| 25 mph (40.23 km/h) | 29.71 mph (47.81 km/h) |
| 30 mph (48.28 km/h) | 35.65 mph (57.38 km/h) |
| 35 mph (56.33 km/h) | 41.59 mph (66.94 km/h) |
| 40 mph (64.37 km/h) | 47.54 mph (76.5 km/h) |
| 45 mph (72.42 km/h) | 53.48 mph (86.07 km/h) |
| 50 mph (80.47 km/h) | 59.42 mph (95.63 km/h) |
| 55 mph (88.51 km/h) | 65.36 mph (105.19 km/h) |
| 60 mph (96.56 km/h) | 71.3 mph (114.75 km/h) |
| 65 mph (104.61 km/h) | 77.25 mph (124.32 km/h) |
| 70 mph (112.65 km/h) | 83.19 mph (133.88 km/h) |
| 75 mph (120.7 km/h) | 89.13 mph (143.44 km/h) |
| 80 mph (128.75 km/h) | 95.07 mph (153.01 km/h) |
| 85 mph (136.79 km/h) | 101.02 mph (162.57 km/h) |
| 90 mph (144.84 km/h) | 106.96 mph (172.13 km/h) |
| 95 mph (152.89 km/h) | 112.9 mph (181.69 km/h) |
| 100 mph (160.93 km/h) | 118.84 mph (191.26 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1659 | 1927 | 2076 | 2167 | 2266 | 2337 | 2414 | 2506 | 2633 | 2760 | 2902 | 3014 | 3219 | 3445 | 3622 | 3735 | 3798 | 4031 | 4356 | 5062 |
Better Fuel Economy Factory Ratios Increased Power
