Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
255/40r18 vs 145/80r17 Tire Comparison Side By Side
  255/40-18 145/80-17 Difference
Diameter inches (mm) 26.03 (661.2) 26.13 (663.8) 0.1 (2.6) 0.4%
Width inches (mm) 10.04 (255) 5.71 (145) -4.33 (-110) -43.1%
Circum. inches (mm) 81.78 (2077.22) 82.1 (2085.39) 0.32 (8.17) 0.4%
Sidewall Height inches (mm) 4.02 (102) 4.57 (116) 0.55 (14) 13.7%
Revolutions per mile (km) 774.76 (481.41) 771.72 (479.53) -3.03 (-1.89) -0.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.08 mph (32.31 km/h)
25 mph (40.23 km/h)25.1 mph (40.39 km/h)
30 mph (48.28 km/h)30.12 mph (48.47 km/h)
35 mph (56.33 km/h)35.14 mph (56.55 km/h)
40 mph (64.37 km/h)40.16 mph (64.63 km/h)
45 mph (72.42 km/h)45.18 mph (72.71 km/h)
50 mph (80.47 km/h)50.2 mph (80.78 km/h)
55 mph (88.51 km/h)55.22 mph (88.86 km/h)
60 mph (96.56 km/h)60.24 mph (96.94 km/h)
65 mph (104.61 km/h)65.26 mph (105.02 km/h)
70 mph (112.65 km/h)70.28 mph (113.1 km/h)
75 mph (120.7 km/h)75.29 mph (121.18 km/h)
80 mph (128.75 km/h)80.31 mph (129.25 km/h)
85 mph (136.79 km/h)85.33 mph (137.33 km/h)
90 mph (144.84 km/h)90.35 mph (145.41 km/h)
95 mph (152.89 km/h)95.37 mph (153.49 km/h)
100 mph (160.93 km/h)100.39 mph (161.57 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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