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235/75r15 vs 31/10.5r15 Tire Comparison Side By Side
 235/75-1531/10.5-15Difference
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 ReadingActual 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)
2.352.732.943.073.213.313.423.553.733.914.114.274.564.885.135.295.385.716.177.17
16571925207321642263233424112503263027572898301032153440361737303793402643505055
Better Fuel Economy Factory Ratios Increased Power

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