| 235/75-15 | 31/10.5-15 | Difference |
Diameter inches (mm) | 28.88 (733.5) | 30.98 (786.84) | 2.1 (53.34) 7.3% |
Width inches (mm) | 9.25 (235) | 10.51 (267) | 1.26 (32) 13.6% |
Circum. inches (mm) | 90.72 (2304.36) | 97.32 (2471.93) | 6.6 (167.57) 7.3% |
Sidewall Height inches (mm) | 6.94 (176.25) | 7.99 (202.92) | 1.05 (26.67) 15.1% |
Revolutions per mile (km) | 698.39 (433.96) | 651.05 (404.54) | -47.34 (-29.42) -6.8% |
Speedometer Difference
Speedo Reading | Actual Speed |
20 mph (32.19 km/h) | 21.45 mph (34.53 km/h) |
25 mph (40.23 km/h) | 26.82 mph (43.16 km/h) |
30 mph (48.28 km/h) | 32.18 mph (51.79 km/h) |
35 mph (56.33 km/h) | 37.55 mph (60.42 km/h) |
40 mph (64.37 km/h) | 42.91 mph (69.06 km/h) |
45 mph (72.42 km/h) | 48.27 mph (77.69 km/h) |
50 mph (80.47 km/h) | 53.64 mph (86.32 km/h) |
55 mph (88.51 km/h) | 59 mph (94.95 km/h) |
60 mph (96.56 km/h) | 64.36 mph (103.58 km/h) |
65 mph (104.61 km/h) | 69.73 mph (112.21 km/h) |
Gear Ratio / RPMs for New Tire (@ 65 mph)
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 |
1657 | 1925 | 2073 | 2164 | 2263 | 2334 | 2411 | 2503 | 2630 | 2757 | 2898 | 3010 | 3215 | 3440 | 3617 | 3730 | 3793 | 4026 | 4350 | 5055 |
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