Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 245/30-21 | 255/30-20 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 26.79 (680.4) | 26.02 (661) | -0.76 (-19.4) -2.9% |
| Width inches (mm) | 9.65 (245) | 10.04 (255) | 0.39 (10) 4.1% |
| Circum. inches (mm) | 84.16 (2137.54) | 81.76 (2076.59) | -2.4 (-60.95) -2.9% |
| Sidewall Height inches (mm) | 2.89 (73.5) | 3.01 (76.5) | 0.12 (3) 4.1% |
| Revolutions per mile (km) | 752.9 (467.83) | 774.99 (481.56) | 22.1 (13.73) 2.9% |
255/30-20 Tires
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 19.43 mph (31.27 km/h) |
| 25 mph (40.23 km/h) | 24.29 mph (39.09 km/h) |
| 30 mph (48.28 km/h) | 29.14 mph (46.9 km/h) |
| 35 mph (56.33 km/h) | 34 mph (54.72 km/h) |
| 40 mph (64.37 km/h) | 38.86 mph (62.54 km/h) |
| 45 mph (72.42 km/h) | 43.72 mph (70.36 km/h) |
| 50 mph (80.47 km/h) | 48.57 mph (78.17 km/h) |
| 55 mph (88.51 km/h) | 53.43 mph (85.99 km/h) |
| 60 mph (96.56 km/h) | 58.29 mph (93.81 km/h) |
| 65 mph (104.61 km/h) | 63.15 mph (101.62 km/h) |
| 70 mph (112.65 km/h) | 68 mph (109.44 km/h) |
| 75 mph (120.7 km/h) | 72.86 mph (117.26 km/h) |
| 80 mph (128.75 km/h) | 77.72 mph (125.08 km/h) |
| 85 mph (136.79 km/h) | 82.58 mph (132.89 km/h) |
| 90 mph (144.84 km/h) | 87.43 mph (140.71 km/h) |
| 95 mph (152.89 km/h) | 92.29 mph (148.53 km/h) |
| 100 mph (160.93 km/h) | 97.15 mph (156.35 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1972 | 2291 | 2467 | 2576 | 2694 | 2778 | 2870 | 2979 | 3130 | 3281 | 3449 | 3584 | 3827 | 4095 | 4305 | 4440 | 4515 | 4792 | 5178 | 6017 |
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