Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
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165/90r18 vs 165/85r18 Tire Comparison Side By Side
  165/90-18 165/85-18 Difference
Diameter inches (mm) 29.69 (754.2) 29.04 (737.7) -0.65 (-16.5) -2.2%
Width inches (mm) 6.5 (165) 6.5 (165) 0 (0) 0%
Circum. inches (mm) 93.28 (2369.39) 91.24 (2317.55) -2.04 (-51.84) -2.2%
Sidewall Height inches (mm) 5.85 (148.5) 5.52 (140.25) -0.32 (-8.25) -5.6%
Revolutions per mile (km) 679.22 (422.05) 694.42 (431.49) 15.19 (9.44) 2.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.56 mph (31.48 km/h)
25 mph (40.23 km/h)24.45 mph (39.35 km/h)
30 mph (48.28 km/h)29.34 mph (47.22 km/h)
35 mph (56.33 km/h)34.23 mph (55.09 km/h)
40 mph (64.37 km/h)39.12 mph (62.97 km/h)
45 mph (72.42 km/h)44.02 mph (70.84 km/h)
50 mph (80.47 km/h)48.91 mph (78.71 km/h)
55 mph (88.51 km/h)53.8 mph (86.58 km/h)
60 mph (96.56 km/h)58.69 mph (94.45 km/h)
65 mph (104.61 km/h)63.58 mph (102.32 km/h)
70 mph (112.65 km/h)68.47 mph (110.19 km/h)
75 mph (120.7 km/h)73.36 mph (118.06 km/h)
80 mph (128.75 km/h)78.25 mph (125.93 km/h)
85 mph (136.79 km/h)83.14 mph (133.8 km/h)
90 mph (144.84 km/h)88.03 mph (141.67 km/h)
95 mph (152.89 km/h)92.92 mph (149.54 km/h)
100 mph (160.93 km/h)97.81 mph (157.41 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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