Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
235/65r18 vs 235/55r18 Tire Comparison Side By Side
  235/65-18 235/55-18 Difference
Diameter inches (mm) 30.03 (762.7) 28.18 (715.7) -1.85 (-47) -6.2%
Width inches (mm) 9.25 (235) 9.25 (235) 0 (0) 0%
Circum. inches (mm) 94.33 (2396.09) 88.52 (2248.44) -5.81 (-147.65) -6.2%
Sidewall Height inches (mm) 6.01 (152.75) 5.09 (129.25) -0.93 (-23.5) -15.4%
Revolutions per mile (km) 671.65 (417.35) 715.76 (444.75) 44.11 (27.41) 6.6%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)18.77 mph (30.2 km/h)
25 mph (40.23 km/h)23.46 mph (37.75 km/h)
30 mph (48.28 km/h)28.15 mph (45.31 km/h)
35 mph (56.33 km/h)32.84 mph (52.86 km/h)
40 mph (64.37 km/h)37.54 mph (60.41 km/h)
45 mph (72.42 km/h)42.23 mph (67.96 km/h)
50 mph (80.47 km/h)46.92 mph (75.51 km/h)
55 mph (88.51 km/h)51.61 mph (83.06 km/h)
60 mph (96.56 km/h)56.3 mph (90.61 km/h)
65 mph (104.61 km/h)60.99 mph (98.16 km/h)
70 mph (112.65 km/h)65.69 mph (105.71 km/h)
75 mph (120.7 km/h)70.38 mph (113.26 km/h)
80 mph (128.75 km/h)75.07 mph (120.81 km/h)
85 mph (136.79 km/h)79.76 mph (128.36 km/h)
90 mph (144.84 km/h)84.45 mph (135.92 km/h)
95 mph (152.89 km/h)89.15 mph (143.47 km/h)
100 mph (160.93 km/h)93.84 mph (151.02 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
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