Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
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145/80r18 vs 245/45r18 Tire Comparison Side By Side
  145/80-18 245/45-18 Difference
Diameter inches (mm) 27.13 (689.2) 26.68 (677.7) -0.45 (-11.5) -1.7%
Width inches (mm) 5.71 (145) 9.65 (245) 3.94 (100) 69%
Circum. inches (mm) 85.24 (2165.19) 83.82 (2129.06) -1.42 (-36.13) -1.7%
Sidewall Height inches (mm) 4.57 (116) 4.34 (110.25) -0.23 (-5.75) -5%
Revolutions per mile (km) 743.28 (461.85) 755.9 (469.69) 12.61 (7.84) 1.7%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.67 mph (31.65 km/h)
25 mph (40.23 km/h)24.58 mph (39.56 km/h)
30 mph (48.28 km/h)29.5 mph (47.47 km/h)
35 mph (56.33 km/h)34.42 mph (55.39 km/h)
40 mph (64.37 km/h)39.33 mph (63.3 km/h)
45 mph (72.42 km/h)44.25 mph (71.21 km/h)
50 mph (80.47 km/h)49.17 mph (79.12 km/h)
55 mph (88.51 km/h)54.08 mph (87.04 km/h)
60 mph (96.56 km/h)59 mph (94.95 km/h)
65 mph (104.61 km/h)63.92 mph (102.86 km/h)
70 mph (112.65 km/h)68.83 mph (110.77 km/h)
75 mph (120.7 km/h)73.75 mph (118.69 km/h)
80 mph (128.75 km/h)78.67 mph (126.6 km/h)
85 mph (136.79 km/h)83.58 mph (134.51 km/h)
90 mph (144.84 km/h)88.5 mph (142.42 km/h)
95 mph (152.89 km/h)93.41 mph (150.34 km/h)
100 mph (160.93 km/h)98.33 mph (158.25 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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