Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
180/60r18 vs 145/60r18 Tire Comparison Side By Side
  180/60-18 145/60-18 Difference
Diameter inches (mm) 26.5 (673.2) 24.85 (631.2) -1.65 (-42) -6.2%
Width inches (mm) 7.09 (180) 5.71 (145) -1.38 (-35) -19.4%
Circum. inches (mm) 83.26 (2114.92) 78.07 (1982.97) -5.19 (-131.95) -6.2%
Sidewall Height inches (mm) 4.25 (108) 3.43 (87) -0.83 (-21) -19.4%
Revolutions per mile (km) 760.95 (472.83) 811.58 (504.29) 50.63 (31.46) 6.7%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)18.75 mph (30.18 km/h)
25 mph (40.23 km/h)23.44 mph (37.72 km/h)
30 mph (48.28 km/h)28.13 mph (45.27 km/h)
35 mph (56.33 km/h)32.82 mph (52.81 km/h)
40 mph (64.37 km/h)37.5 mph (60.36 km/h)
45 mph (72.42 km/h)42.19 mph (67.9 km/h)
50 mph (80.47 km/h)46.88 mph (75.45 km/h)
55 mph (88.51 km/h)51.57 mph (82.99 km/h)
60 mph (96.56 km/h)56.26 mph (90.54 km/h)
65 mph (104.61 km/h)60.94 mph (98.08 km/h)
70 mph (112.65 km/h)65.63 mph (105.63 km/h)
75 mph (120.7 km/h)70.32 mph (113.17 km/h)
80 mph (128.75 km/h)75.01 mph (120.72 km/h)
85 mph (136.79 km/h)79.7 mph (128.26 km/h)
90 mph (144.84 km/h)84.39 mph (135.8 km/h)
95 mph (152.89 km/h)89.07 mph (143.35 km/h)
100 mph (160.93 km/h)93.76 mph (150.89 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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