Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 120/70-21 | 90/90-21 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 27.61 (701.4) | 27.38 (695.4) | -0.24 (-6) -0.9% |
| Width inches (mm) | 4.72 (120) | 3.54 (90) | -1.18 (-30) -25% |
| Circum. inches (mm) | 86.75 (2203.51) | 86.01 (2184.66) | -0.74 (-18.85) -0.9% |
| Sidewall Height inches (mm) | 3.31 (84) | 3.19 (81) | -0.12 (-3) -3.6% |
| Revolutions per mile (km) | 730.35 (453.82) | 736.66 (457.74) | 6.3 (3.92) 0.9% |
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 19.83 mph (31.91 km/h) |
| 25 mph (40.23 km/h) | 24.79 mph (39.89 km/h) |
| 30 mph (48.28 km/h) | 29.74 mph (47.87 km/h) |
| 35 mph (56.33 km/h) | 34.7 mph (55.85 km/h) |
| 40 mph (64.37 km/h) | 39.66 mph (63.82 km/h) |
| 45 mph (72.42 km/h) | 44.62 mph (71.8 km/h) |
| 50 mph (80.47 km/h) | 49.57 mph (79.78 km/h) |
| 55 mph (88.51 km/h) | 54.53 mph (87.76 km/h) |
| 60 mph (96.56 km/h) | 59.49 mph (95.73 km/h) |
| 65 mph (104.61 km/h) | 64.44 mph (103.71 km/h) |
| 70 mph (112.65 km/h) | 69.4 mph (111.69 km/h) |
| 75 mph (120.7 km/h) | 74.36 mph (119.67 km/h) |
| 80 mph (128.75 km/h) | 79.32 mph (127.65 km/h) |
| 85 mph (136.79 km/h) | 84.27 mph (135.62 km/h) |
| 90 mph (144.84 km/h) | 89.23 mph (143.6 km/h) |
| 95 mph (152.89 km/h) | 94.19 mph (151.58 km/h) |
| 100 mph (160.93 km/h) | 99.14 mph (159.56 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1875 | 2178 | 2345 | 2449 | 2561 | 2640 | 2728 | 2832 | 2976 | 3119 | 3279 | 3406 | 3638 | 3893 | 4092 | 4220 | 4292 | 4555 | 4922 | 5720 |
Better Fuel Economy Factory Ratios Increased Power
