Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
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165/90r18 vs 285/45r20 Tire Comparison Side By Side
  165/90-18 285/45-20 Difference
Diameter inches (mm) 29.69 (754.2) 30.1 (764.5) 0.41 (10.3) 1.4%
Width inches (mm) 6.5 (165) 11.22 (285) 4.72 (120) 72.7%
Circum. inches (mm) 93.28 (2369.39) 94.56 (2401.75) 1.27 (32.36) 1.4%
Sidewall Height inches (mm) 5.85 (148.5) 5.05 (128.25) -0.8 (-20.25) -13.6%
Revolutions per mile (km) 679.22 (422.05) 670.07 (416.36) -9.15 (-5.69) -1.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.27 mph (32.63 km/h)
25 mph (40.23 km/h)25.34 mph (40.78 km/h)
30 mph (48.28 km/h)30.41 mph (48.94 km/h)
35 mph (56.33 km/h)35.48 mph (57.1 km/h)
40 mph (64.37 km/h)40.55 mph (65.25 km/h)
45 mph (72.42 km/h)45.61 mph (73.41 km/h)
50 mph (80.47 km/h)50.68 mph (81.57 km/h)
55 mph (88.51 km/h)55.75 mph (89.72 km/h)
60 mph (96.56 km/h)60.82 mph (97.88 km/h)
65 mph (104.61 km/h)65.89 mph (106.04 km/h)
70 mph (112.65 km/h)70.96 mph (114.19 km/h)
75 mph (120.7 km/h)76.02 mph (122.35 km/h)
80 mph (128.75 km/h)81.09 mph (130.51 km/h)
85 mph (136.79 km/h)86.16 mph (138.66 km/h)
90 mph (144.84 km/h)91.23 mph (146.82 km/h)
95 mph (152.89 km/h)96.3 mph (154.98 km/h)
100 mph (160.93 km/h)101.37 mph (163.13 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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