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 155/90r18 Tire Comparison Side By Side
  145/80-18 155/90-18 Difference
Diameter inches (mm) 27.13 (689.2) 28.98 (736.2) 1.85 (47) 6.8%
Width inches (mm) 5.71 (145) 6.1 (155) 0.39 (10) 6.9%
Circum. inches (mm) 85.24 (2165.19) 91.06 (2312.84) 5.81 (147.65) 6.8%
Sidewall Height inches (mm) 4.57 (116) 5.49 (139.5) 0.93 (23.5) 20.3%
Revolutions per mile (km) 743.28 (461.85) 695.83 (432.37) -47.45 (-29.49) -6.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)21.36 mph (34.38 km/h)
25 mph (40.23 km/h)26.7 mph (42.98 km/h)
30 mph (48.28 km/h)32.05 mph (51.57 km/h)
35 mph (56.33 km/h)37.39 mph (60.17 km/h)
40 mph (64.37 km/h)42.73 mph (68.76 km/h)
45 mph (72.42 km/h)48.07 mph (77.36 km/h)
50 mph (80.47 km/h)53.41 mph (85.95 km/h)
55 mph (88.51 km/h)58.75 mph (94.55 km/h)
60 mph (96.56 km/h)64.09 mph (103.15 km/h)
65 mph (104.61 km/h)69.43 mph (111.74 km/h)
70 mph (112.65 km/h)74.77 mph (120.34 km/h)
75 mph (120.7 km/h)80.11 mph (128.93 km/h)
80 mph (128.75 km/h)85.46 mph (137.53 km/h)
85 mph (136.79 km/h)90.8 mph (146.12 km/h)
90 mph (144.84 km/h)96.14 mph (154.72 km/h)
95 mph (152.89 km/h)101.48 mph (163.31 km/h)
100 mph (160.93 km/h)106.82 mph (171.91 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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