Tire Size Finder (optional):
Stock Sizes
- 255/75-16
Plus Sizes
- 255/75-16
Accepts P-Metric and Inches
| 235/30-20 | 255/40-20 | Difference | |
|---|---|---|---|
| Diameter inches (mm) | 25.55 (649) | 28.03 (712) | 2.48 (63) 9.7% |
| Width inches (mm) | 9.25 (235) | 10.04 (255) | 0.79 (20) 8.5% |
| Circum. inches (mm) | 80.27 (2038.89) | 88.06 (2236.81) | 7.79 (197.92) 9.7% |
| Sidewall Height inches (mm) | 2.78 (70.5) | 4.02 (102) | 1.24 (31.5) 44.7% |
| Revolutions per mile (km) | 789.32 (490.46) | 719.48 (447.06) | -69.84 (-43.4) -8.8% |
255/40-20 Tires
Speedometer Difference
| Speedo Reading | Actual Speed |
|---|---|
| 20 mph (32.19 km/h) | 21.94 mph (35.31 km/h) |
| 25 mph (40.23 km/h) | 27.43 mph (44.14 km/h) |
| 30 mph (48.28 km/h) | 32.91 mph (52.97 km/h) |
| 35 mph (56.33 km/h) | 38.4 mph (61.79 km/h) |
| 40 mph (64.37 km/h) | 43.88 mph (70.62 km/h) |
| 45 mph (72.42 km/h) | 49.37 mph (79.45 km/h) |
| 50 mph (80.47 km/h) | 54.85 mph (88.28 km/h) |
| 55 mph (88.51 km/h) | 60.34 mph (97.11 km/h) |
| 60 mph (96.56 km/h) | 65.82 mph (105.93 km/h) |
| 65 mph (104.61 km/h) | 71.31 mph (114.76 km/h) |
| 70 mph (112.65 km/h) | 76.8 mph (123.59 km/h) |
| 75 mph (120.7 km/h) | 82.28 mph (132.42 km/h) |
| 80 mph (128.75 km/h) | 87.77 mph (141.25 km/h) |
| 85 mph (136.79 km/h) | 93.25 mph (150.07 km/h) |
| 90 mph (144.84 km/h) | 98.74 mph (158.9 km/h) |
| 95 mph (152.89 km/h) | 104.22 mph (167.73 km/h) |
| 100 mph (160.93 km/h) | 109.71 mph (176.56 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1831 | 2127 | 2291 | 2392 | 2501 | 2579 | 2665 | 2766 | 2906 | 3046 | 3202 | 3327 | 3553 | 3802 | 3997 | 4122 | 4192 | 4449 | 4807 | 5586 |
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