Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 285/45-21 | 305/40-21 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 31.1 (789.9) | 30.61 (777.4) | -0.49 (-12.5) -1.6% |
| Width inches (mm) | 11.22 (285) | 12.01 (305) | 0.79 (20) 7% |
| Circum. inches (mm) | 97.7 (2481.54) | 96.15 (2442.27) | -1.55 (-39.27) -1.6% |
| Sidewall Height inches (mm) | 5.05 (128.25) | 4.8 (122) | -0.25 (-6.25) -4.9% |
| Revolutions per mile (km) | 648.53 (402.97) | 658.95 (409.45) | 10.43 (6.48) 1.6% |
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 19.68 mph (31.68 km/h) |
| 25 mph (40.23 km/h) | 24.6 mph (39.6 km/h) |
| 30 mph (48.28 km/h) | 29.53 mph (47.52 km/h) |
| 35 mph (56.33 km/h) | 34.45 mph (55.44 km/h) |
| 40 mph (64.37 km/h) | 39.37 mph (63.36 km/h) |
| 45 mph (72.42 km/h) | 44.29 mph (71.27 km/h) |
| 50 mph (80.47 km/h) | 49.21 mph (79.19 km/h) |
| 55 mph (88.51 km/h) | 54.13 mph (87.11 km/h) |
| 60 mph (96.56 km/h) | 59.05 mph (95.03 km/h) |
| 65 mph (104.61 km/h) | 63.97 mph (102.95 km/h) |
| 70 mph (112.65 km/h) | 68.89 mph (110.87 km/h) |
| 75 mph (120.7 km/h) | 73.81 mph (118.79 km/h) |
| 80 mph (128.75 km/h) | 78.73 mph (126.71 km/h) |
| 85 mph (136.79 km/h) | 83.65 mph (134.63 km/h) |
| 90 mph (144.84 km/h) | 88.58 mph (142.55 km/h) |
| 95 mph (152.89 km/h) | 93.5 mph (150.47 km/h) |
| 100 mph (160.93 km/h) | 98.42 mph (158.39 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1677 | 1948 | 2098 | 2191 | 2291 | 2362 | 2440 | 2533 | 2662 | 2790 | 2933 | 3047 | 3254 | 3482 | 3661 | 3775 | 3839 | 4075 | 4403 | 5116 |
Better Fuel Economy Factory Ratios Increased Power
