Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
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165/55r12 vs 185/40r12 Tire Comparison Side By Side
  165/55-12 185/40-12 Difference
Diameter inches (mm) 19.15 (486.3) 17.83 (452.8) -1.32 (-33.5) -6.9%
Width inches (mm) 6.5 (165) 7.28 (185) 0.79 (20) 12.1%
Circum. inches (mm) 60.15 (1527.76) 56 (1422.51) -4.14 (-105.24) -6.9%
Sidewall Height inches (mm) 3.57 (90.75) 2.91 (74) -0.66 (-16.75) -18.5%
Revolutions per mile (km) 1053.4 (654.55) 1131.34 (702.98) 77.94 (48.43) 7.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)18.62 mph (29.97 km/h)
25 mph (40.23 km/h)23.28 mph (37.46 km/h)
30 mph (48.28 km/h)27.93 mph (44.95 km/h)
35 mph (56.33 km/h)32.59 mph (52.45 km/h)
40 mph (64.37 km/h)37.24 mph (59.94 km/h)
45 mph (72.42 km/h)41.9 mph (67.43 km/h)
50 mph (80.47 km/h)46.56 mph (74.92 km/h)
55 mph (88.51 km/h)51.21 mph (82.42 km/h)
60 mph (96.56 km/h)55.87 mph (89.91 km/h)
65 mph (104.61 km/h)60.52 mph (97.4 km/h)
70 mph (112.65 km/h)65.18 mph (104.89 km/h)
75 mph (120.7 km/h)69.83 mph (112.39 km/h)
80 mph (128.75 km/h)74.49 mph (119.88 km/h)
85 mph (136.79 km/h)79.14 mph (127.37 km/h)
90 mph (144.84 km/h)83.8 mph (134.86 km/h)
95 mph (152.89 km/h)88.46 mph (142.36 km/h)
100 mph (160.93 km/h)93.11 mph (149.85 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
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
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