Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 245/45-20 | 255/40-21 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 28.68 (728.5) | 29.03 (737.4) | 0.35 (8.9) 1.2% |
| Width inches (mm) | 9.65 (245) | 10.04 (255) | 0.39 (10) 4.1% |
| Circum. inches (mm) | 90.1 (2288.65) | 91.21 (2316.61) | 1.1 (27.96) 1.2% |
| Sidewall Height inches (mm) | 4.34 (110.25) | 4.02 (102) | -0.32 (-8.25) -7.5% |
| Revolutions per mile (km) | 703.18 (436.94) | 694.7 (431.66) | -8.49 (-5.27) -1.2% |
255/40-21 Tires
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 20.24 mph (32.58 km/h) |
| 25 mph (40.23 km/h) | 25.31 mph (40.73 km/h) |
| 30 mph (48.28 km/h) | 30.37 mph (48.87 km/h) |
| 35 mph (56.33 km/h) | 35.43 mph (57.02 km/h) |
| 40 mph (64.37 km/h) | 40.49 mph (65.16 km/h) |
| 45 mph (72.42 km/h) | 45.55 mph (73.31 km/h) |
| 50 mph (80.47 km/h) | 50.61 mph (81.45 km/h) |
| 55 mph (88.51 km/h) | 55.67 mph (89.6 km/h) |
| 60 mph (96.56 km/h) | 60.73 mph (97.74 km/h) |
| 65 mph (104.61 km/h) | 65.79 mph (105.89 km/h) |
| 70 mph (112.65 km/h) | 70.86 mph (114.03 km/h) |
| 75 mph (120.7 km/h) | 75.92 mph (122.18 km/h) |
| 80 mph (128.75 km/h) | 80.98 mph (130.32 km/h) |
| 85 mph (136.79 km/h) | 86.04 mph (138.47 km/h) |
| 90 mph (144.84 km/h) | 91.1 mph (146.61 km/h) |
| 95 mph (152.89 km/h) | 96.16 mph (154.76 km/h) |
| 100 mph (160.93 km/h) | 101.22 mph (162.9 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1768 | 2054 | 2212 | 2310 | 2415 | 2490 | 2573 | 2671 | 2806 | 2941 | 3092 | 3212 | 3430 | 3671 | 3859 | 3980 | 4047 | 4296 | 4642 | 5394 |
Better Fuel Economy Factory Ratios Increased Power
