Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 305/30-21 | 305/30-20 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 28.2 (716.4) | 27.2 (691) | -1 (-25.4) -3.5% |
| Width inches (mm) | 12.01 (305) | 12.01 (305) | 0 (0) 0% |
| Circum. inches (mm) | 88.61 (2250.64) | 85.47 (2170.84) | -3.14 (-79.8) -3.5% |
| Sidewall Height inches (mm) | 3.6 (91.5) | 3.6 (91.5) | 0 (0) 0% |
| Revolutions per mile (km) | 715.06 (444.32) | 741.35 (460.65) | 26.28 (16.33) 3.7% |
305/30-20 Tires
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 19.29 mph (31.05 km/h) |
| 25 mph (40.23 km/h) | 24.11 mph (38.81 km/h) |
| 30 mph (48.28 km/h) | 28.94 mph (46.57 km/h) |
| 35 mph (56.33 km/h) | 33.76 mph (54.33 km/h) |
| 40 mph (64.37 km/h) | 38.58 mph (62.09 km/h) |
| 45 mph (72.42 km/h) | 43.4 mph (69.85 km/h) |
| 50 mph (80.47 km/h) | 48.23 mph (77.61 km/h) |
| 55 mph (88.51 km/h) | 53.05 mph (85.38 km/h) |
| 60 mph (96.56 km/h) | 57.87 mph (93.14 km/h) |
| 65 mph (104.61 km/h) | 62.7 mph (100.9 km/h) |
| 70 mph (112.65 km/h) | 67.52 mph (108.66 km/h) |
| 75 mph (120.7 km/h) | 72.34 mph (116.42 km/h) |
| 80 mph (128.75 km/h) | 77.16 mph (124.18 km/h) |
| 85 mph (136.79 km/h) | 81.99 mph (131.94 km/h) |
| 90 mph (144.84 km/h) | 86.81 mph (139.71 km/h) |
| 95 mph (152.89 km/h) | 91.63 mph (147.47 km/h) |
| 100 mph (160.93 km/h) | 96.45 mph (155.23 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1887 | 2192 | 2360 | 2465 | 2577 | 2657 | 2746 | 2850 | 2994 | 3139 | 3300 | 3428 | 3661 | 3918 | 4118 | 4247 | 4319 | 4584 | 4953 | 5756 |
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