Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 285/30-21 | 255/30-21 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 27.73 (704.4) | 27.02 (686.4) | -0.71 (-18) -2.6% |
| Width inches (mm) | 11.22 (285) | 10.04 (255) | -1.18 (-30) -10.5% |
| Circum. inches (mm) | 87.12 (2212.94) | 84.9 (2156.39) | -2.23 (-56.55) -2.6% |
| Sidewall Height inches (mm) | 3.37 (85.5) | 3.01 (76.5) | -0.35 (-9) -10.5% |
| Revolutions per mile (km) | 727.24 (451.89) | 746.31 (463.74) | 19.07 (11.85) 2.6% |
255/30-21 Tires
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 19.49 mph (31.36 km/h) |
| 25 mph (40.23 km/h) | 24.36 mph (39.21 km/h) |
| 30 mph (48.28 km/h) | 29.23 mph (47.05 km/h) |
| 35 mph (56.33 km/h) | 34.11 mph (54.89 km/h) |
| 40 mph (64.37 km/h) | 38.98 mph (62.73 km/h) |
| 45 mph (72.42 km/h) | 43.85 mph (70.57 km/h) |
| 50 mph (80.47 km/h) | 48.72 mph (78.41 km/h) |
| 55 mph (88.51 km/h) | 53.59 mph (86.25 km/h) |
| 60 mph (96.56 km/h) | 58.47 mph (94.09 km/h) |
| 65 mph (104.61 km/h) | 63.34 mph (101.93 km/h) |
| 70 mph (112.65 km/h) | 68.21 mph (109.78 km/h) |
| 75 mph (120.7 km/h) | 73.08 mph (117.62 km/h) |
| 80 mph (128.75 km/h) | 77.96 mph (125.46 km/h) |
| 85 mph (136.79 km/h) | 82.83 mph (133.3 km/h) |
| 90 mph (144.84 km/h) | 87.7 mph (141.14 km/h) |
| 95 mph (152.89 km/h) | 92.57 mph (148.98 km/h) |
| 100 mph (160.93 km/h) | 97.44 mph (156.82 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1899 | 2206 | 2376 | 2481 | 2594 | 2675 | 2764 | 2869 | 3015 | 3160 | 3322 | 3451 | 3685 | 3944 | 4146 | 4275 | 4348 | 4615 | 4986 | 5795 |
Better Fuel Economy Factory Ratios Increased Power
