Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
120/100r18 vs 100/90r18 Tire Comparison Side By Side
  120/100-18 100/90-18 Difference
Diameter inches (mm) 27.45 (697.2) 25.09 (637.2) -2.36 (-60) -8.6%
Width inches (mm) 4.72 (120) 3.94 (100) -0.79 (-20) -16.7%
Circum. inches (mm) 86.23 (2190.32) 78.81 (2001.82) -7.42 (-188.5) -8.6%
Sidewall Height inches (mm) 4.72 (120) 3.54 (90) -1.18 (-30) -25%
Revolutions per mile (km) 734.75 (456.55) 803.94 (499.54) 69.19 (42.99) 9.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)18.28 mph (29.42 km/h)
25 mph (40.23 km/h)22.85 mph (36.77 km/h)
30 mph (48.28 km/h)27.42 mph (44.13 km/h)
35 mph (56.33 km/h)31.99 mph (51.48 km/h)
40 mph (64.37 km/h)36.56 mph (58.83 km/h)
45 mph (72.42 km/h)41.13 mph (66.19 km/h)
50 mph (80.47 km/h)45.7 mph (73.54 km/h)
55 mph (88.51 km/h)50.27 mph (80.9 km/h)
60 mph (96.56 km/h)54.84 mph (88.25 km/h)
65 mph (104.61 km/h)59.41 mph (95.61 km/h)
70 mph (112.65 km/h)63.98 mph (102.96 km/h)
75 mph (120.7 km/h)68.55 mph (110.31 km/h)
80 mph (128.75 km/h)73.12 mph (117.67 km/h)
85 mph (136.79 km/h)77.69 mph (125.02 km/h)
90 mph (144.84 km/h)82.25 mph (132.38 km/h)
95 mph (152.89 km/h)86.82 mph (139.73 km/h)
100 mph (160.93 km/h)91.39 mph (147.08 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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