Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 285/30-21 | 315/40-21 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 27.73 (704.4) | 30.92 (785.4) | 3.19 (81) 11.5% |
| Width inches (mm) | 11.22 (285) | 12.4 (315) | 1.18 (30) 10.5% |
| Circum. inches (mm) | 87.12 (2212.94) | 97.14 (2467.41) | 10.02 (254.47) 11.5% |
| Sidewall Height inches (mm) | 3.37 (85.5) | 4.96 (126) | 1.59 (40.5) 47.4% |
| Revolutions per mile (km) | 727.24 (451.89) | 652.24 (405.28) | -75 (-46.6) -10.3% |
315/40-21 Tires
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 22.3 mph (35.89 km/h) |
| 25 mph (40.23 km/h) | 27.87 mph (44.86 km/h) |
| 30 mph (48.28 km/h) | 33.45 mph (53.83 km/h) |
| 35 mph (56.33 km/h) | 39.02 mph (62.8 km/h) |
| 40 mph (64.37 km/h) | 44.6 mph (71.78 km/h) |
| 45 mph (72.42 km/h) | 50.17 mph (80.75 km/h) |
| 50 mph (80.47 km/h) | 55.75 mph (89.72 km/h) |
| 55 mph (88.51 km/h) | 61.32 mph (98.69 km/h) |
| 60 mph (96.56 km/h) | 66.9 mph (107.66 km/h) |
| 65 mph (104.61 km/h) | 72.47 mph (116.64 km/h) |
| 70 mph (112.65 km/h) | 78.05 mph (125.61 km/h) |
| 75 mph (120.7 km/h) | 83.62 mph (134.58 km/h) |
| 80 mph (128.75 km/h) | 89.2 mph (143.55 km/h) |
| 85 mph (136.79 km/h) | 94.77 mph (152.52 km/h) |
| 90 mph (144.84 km/h) | 100.35 mph (161.5 km/h) |
| 95 mph (152.89 km/h) | 105.92 mph (170.47 km/h) |
| 100 mph (160.93 km/h) | 111.5 mph (179.44 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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