Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 325/30-21 | 315/30-21 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 28.68 (728.4) | 28.44 (722.4) | -0.24 (-6) -0.8% |
| Width inches (mm) | 12.8 (325) | 12.4 (315) | -0.39 (-10) -3.1% |
| Circum. inches (mm) | 90.09 (2288.34) | 89.35 (2269.49) | -0.74 (-18.85) -0.8% |
| Sidewall Height inches (mm) | 3.84 (97.5) | 3.72 (94.5) | -0.12 (-3) -3.1% |
| Revolutions per mile (km) | 703.28 (437) | 709.12 (440.63) | 5.84 (3.63) 0.8% |
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 19.84 mph (31.92 km/h) |
| 25 mph (40.23 km/h) | 24.79 mph (39.9 km/h) |
| 30 mph (48.28 km/h) | 29.75 mph (47.88 km/h) |
| 35 mph (56.33 km/h) | 34.71 mph (55.86 km/h) |
| 40 mph (64.37 km/h) | 39.67 mph (63.84 km/h) |
| 45 mph (72.42 km/h) | 44.63 mph (71.82 km/h) |
| 50 mph (80.47 km/h) | 49.59 mph (79.8 km/h) |
| 55 mph (88.51 km/h) | 54.55 mph (87.78 km/h) |
| 60 mph (96.56 km/h) | 59.51 mph (95.77 km/h) |
| 65 mph (104.61 km/h) | 64.46 mph (103.75 km/h) |
| 70 mph (112.65 km/h) | 69.42 mph (111.73 km/h) |
| 75 mph (120.7 km/h) | 74.38 mph (119.71 km/h) |
| 80 mph (128.75 km/h) | 79.34 mph (127.69 km/h) |
| 85 mph (136.79 km/h) | 84.3 mph (135.67 km/h) |
| 90 mph (144.84 km/h) | 89.26 mph (143.65 km/h) |
| 95 mph (152.89 km/h) | 94.22 mph (151.63 km/h) |
| 100 mph (160.93 km/h) | 99.18 mph (159.61 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1805 | 2096 | 2258 | 2357 | 2465 | 2542 | 2626 | 2726 | 2864 | 3003 | 3156 | 3279 | 3502 | 3747 | 3939 | 4062 | 4131 | 4385 | 4738 | 5506 |
Better Fuel Economy Factory Ratios Increased Power
