Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
175/90r18 vs 185/90r18 Tire Comparison Side By Side
  175/90-18 185/90-18 Difference
Diameter inches (mm) 30.4 (772.2) 31.11 (790.2) 0.71 (18) 2.3%
Width inches (mm) 6.89 (175) 7.28 (185) 0.39 (10) 5.7%
Circum. inches (mm) 95.51 (2425.94) 97.74 (2482.49) 2.23 (56.55) 2.3%
Sidewall Height inches (mm) 6.2 (157.5) 6.56 (166.5) 0.35 (9) 5.7%
Revolutions per mile (km) 663.39 (412.21) 648.28 (402.82) -15.11 (-9.39) -2.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.47 mph (32.94 km/h)
25 mph (40.23 km/h)25.58 mph (41.17 km/h)
30 mph (48.28 km/h)30.7 mph (49.41 km/h)
35 mph (56.33 km/h)35.82 mph (57.64 km/h)
40 mph (64.37 km/h)40.93 mph (65.87 km/h)
45 mph (72.42 km/h)46.05 mph (74.11 km/h)
50 mph (80.47 km/h)51.17 mph (82.34 km/h)
55 mph (88.51 km/h)56.28 mph (90.58 km/h)
60 mph (96.56 km/h)61.4 mph (98.81 km/h)
65 mph (104.61 km/h)66.52 mph (107.05 km/h)
70 mph (112.65 km/h)71.63 mph (115.28 km/h)
75 mph (120.7 km/h)76.75 mph (123.51 km/h)
80 mph (128.75 km/h)81.86 mph (131.75 km/h)
85 mph (136.79 km/h)86.98 mph (139.98 km/h)
90 mph (144.84 km/h)92.1 mph (148.22 km/h)
95 mph (152.89 km/h)97.21 mph (156.45 km/h)
100 mph (160.93 km/h)102.33 mph (164.69 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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