Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 285/30-21 | 285/30-20 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 27.73 (704.4) | 26.73 (679) | -1 (-25.4) -3.6% |
| Width inches (mm) | 11.22 (285) | 11.22 (285) | 0 (0) 0% |
| Circum. inches (mm) | 87.12 (2212.94) | 83.98 (2133.14) | -3.14 (-79.8) -3.6% |
| Sidewall Height inches (mm) | 3.37 (85.5) | 3.37 (85.5) | 0 (0) 0% |
| Revolutions per mile (km) | 727.24 (451.89) | 754.45 (468.79) | 27.2 (16.9) 3.7% |
285/30-20 Tires
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 19.28 mph (31.03 km/h) |
| 25 mph (40.23 km/h) | 24.1 mph (38.78 km/h) |
| 30 mph (48.28 km/h) | 28.92 mph (46.54 km/h) |
| 35 mph (56.33 km/h) | 33.74 mph (54.3 km/h) |
| 40 mph (64.37 km/h) | 38.56 mph (62.05 km/h) |
| 45 mph (72.42 km/h) | 43.38 mph (69.81 km/h) |
| 50 mph (80.47 km/h) | 48.2 mph (77.57 km/h) |
| 55 mph (88.51 km/h) | 53.02 mph (85.32 km/h) |
| 60 mph (96.56 km/h) | 57.84 mph (93.08 km/h) |
| 65 mph (104.61 km/h) | 62.66 mph (100.84 km/h) |
| 70 mph (112.65 km/h) | 67.48 mph (108.59 km/h) |
| 75 mph (120.7 km/h) | 72.3 mph (116.35 km/h) |
| 80 mph (128.75 km/h) | 77.12 mph (124.11 km/h) |
| 85 mph (136.79 km/h) | 81.93 mph (131.86 km/h) |
| 90 mph (144.84 km/h) | 86.75 mph (139.62 km/h) |
| 95 mph (152.89 km/h) | 91.57 mph (147.37 km/h) |
| 100 mph (160.93 km/h) | 96.39 mph (155.13 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1920 | 2230 | 2402 | 2508 | 2623 | 2704 | 2794 | 2900 | 3047 | 3194 | 3358 | 3489 | 3725 | 3987 | 4191 | 4322 | 4395 | 4665 | 5041 | 5858 |
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