Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
155/90r18 vs 235/65r18 Tire Comparison Side By Side
  155/90-18 235/65-18 Difference
Diameter inches (mm) 28.98 (736.2) 30.03 (762.7) 1.04 (26.5) 3.6%
Width inches (mm) 6.1 (155) 9.25 (235) 3.15 (80) 51.6%
Circum. inches (mm) 91.06 (2312.84) 94.33 (2396.09) 3.28 (83.25) 3.6%
Sidewall Height inches (mm) 5.49 (139.5) 6.01 (152.75) 0.52 (13.25) 9.5%
Revolutions per mile (km) 695.83 (432.37) 671.65 (417.35) -24.18 (-15.02) -3.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.72 mph (33.35 km/h)
25 mph (40.23 km/h)25.9 mph (41.68 km/h)
30 mph (48.28 km/h)31.08 mph (50.02 km/h)
35 mph (56.33 km/h)36.26 mph (58.35 km/h)
40 mph (64.37 km/h)41.44 mph (66.69 km/h)
45 mph (72.42 km/h)46.62 mph (75.03 km/h)
50 mph (80.47 km/h)51.8 mph (83.36 km/h)
55 mph (88.51 km/h)56.98 mph (91.7 km/h)
60 mph (96.56 km/h)62.16 mph (100.04 km/h)
65 mph (104.61 km/h)67.34 mph (108.37 km/h)
70 mph (112.65 km/h)72.52 mph (116.71 km/h)
75 mph (120.7 km/h)77.7 mph (125.05 km/h)
80 mph (128.75 km/h)82.88 mph (133.38 km/h)
85 mph (136.79 km/h)88.06 mph (141.72 km/h)
90 mph (144.84 km/h)93.24 mph (150.05 km/h)
95 mph (152.89 km/h)98.42 mph (158.39 km/h)
100 mph (160.93 km/h)103.6 mph (166.73 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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