Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
145/80r18 vs 235/50r18 Tire Comparison Side By Side
  145/80-18 235/50-18 Difference
Diameter inches (mm) 27.13 (689.2) 27.25 (692.2) 0.12 (3) 0.4%
Width inches (mm) 5.71 (145) 9.25 (235) 3.54 (90) 62.1%
Circum. inches (mm) 85.24 (2165.19) 85.61 (2174.61) 0.37 (9.42) 0.4%
Sidewall Height inches (mm) 4.57 (116) 4.63 (117.5) 0.06 (1.5) 1.3%
Revolutions per mile (km) 743.28 (461.85) 740.06 (459.85) -3.22 (-2) -0.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.09 mph (32.33 km/h)
25 mph (40.23 km/h)25.11 mph (40.41 km/h)
30 mph (48.28 km/h)30.13 mph (48.49 km/h)
35 mph (56.33 km/h)35.15 mph (56.57 km/h)
40 mph (64.37 km/h)40.17 mph (64.65 km/h)
45 mph (72.42 km/h)45.2 mph (72.74 km/h)
50 mph (80.47 km/h)50.22 mph (80.82 km/h)
55 mph (88.51 km/h)55.24 mph (88.9 km/h)
60 mph (96.56 km/h)60.26 mph (96.98 km/h)
65 mph (104.61 km/h)65.28 mph (105.06 km/h)
70 mph (112.65 km/h)70.3 mph (113.14 km/h)
75 mph (120.7 km/h)75.33 mph (121.23 km/h)
80 mph (128.75 km/h)80.35 mph (129.31 km/h)
85 mph (136.79 km/h)85.37 mph (137.39 km/h)
90 mph (144.84 km/h)90.39 mph (145.47 km/h)
95 mph (152.89 km/h)95.41 mph (153.55 km/h)
100 mph (160.93 km/h)100.44 mph (161.64 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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