Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 285/40-21 | 315/40-21 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 29.98 (761.4) | 30.92 (785.4) | 0.94 (24) 3.2% |
| Width inches (mm) | 11.22 (285) | 12.4 (315) | 1.18 (30) 10.5% |
| Circum. inches (mm) | 94.17 (2392.01) | 97.14 (2467.41) | 2.97 (75.4) 3.2% |
| Sidewall Height inches (mm) | 4.49 (114) | 4.96 (126) | 0.47 (12) 10.5% |
| Revolutions per mile (km) | 672.8 (418.06) | 652.24 (405.28) | -20.56 (-12.77) -3.1% |
315/40-21 Tires
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 20.63 mph (33.2 km/h) |
| 25 mph (40.23 km/h) | 25.79 mph (41.5 km/h) |
| 30 mph (48.28 km/h) | 30.95 mph (49.8 km/h) |
| 35 mph (56.33 km/h) | 36.1 mph (58.1 km/h) |
| 40 mph (64.37 km/h) | 41.26 mph (66.4 km/h) |
| 45 mph (72.42 km/h) | 46.42 mph (74.7 km/h) |
| 50 mph (80.47 km/h) | 51.58 mph (83 km/h) |
| 55 mph (88.51 km/h) | 56.73 mph (91.3 km/h) |
| 60 mph (96.56 km/h) | 61.89 mph (99.6 km/h) |
| 65 mph (104.61 km/h) | 67.05 mph (107.9 km/h) |
| 70 mph (112.65 km/h) | 72.21 mph (116.21 km/h) |
| 75 mph (120.7 km/h) | 77.36 mph (124.51 km/h) |
| 80 mph (128.75 km/h) | 82.52 mph (132.81 km/h) |
| 85 mph (136.79 km/h) | 87.68 mph (141.11 km/h) |
| 90 mph (144.84 km/h) | 92.84 mph (149.41 km/h) |
| 95 mph (152.89 km/h) | 97.99 mph (157.71 km/h) |
| 100 mph (160.93 km/h) | 103.15 mph (166.01 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1660 | 1928 | 2077 | 2168 | 2267 | 2338 | 2416 | 2507 | 2635 | 2762 | 2903 | 3016 | 3221 | 3447 | 3623 | 3736 | 3800 | 4033 | 4358 | 5064 |
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