Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
37/12.5r18 vs 37/12.5r20 Tire Comparison Side By Side
  37/12.5-18 37/12.5-20 Difference
Diameter inches (mm) 37.03 (940.56) 37.03 (940.48) -0 (-0.08) -0%
Width inches (mm) 12.52 (318) 12.52 (318) 0 (0) 0%
Circum. inches (mm) 116.33 (2954.86) 116.32 (2954.61) -0.01 (-0.25) -0%
Sidewall Height inches (mm) 9.51 (241.68) 8.51 (216.24) -1 (-25.44) -10.5%
Revolutions per mile (km) 544.64 (338.43) 544.69 (338.45) 0.05 (0.03) 0%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20 mph (32.18 km/h)
25 mph (40.23 km/h)25 mph (40.23 km/h)
30 mph (48.28 km/h)30 mph (48.28 km/h)
35 mph (56.33 km/h)35 mph (56.32 km/h)
40 mph (64.37 km/h)40 mph (64.37 km/h)
45 mph (72.42 km/h)45 mph (72.41 km/h)
50 mph (80.47 km/h)50 mph (80.46 km/h)
55 mph (88.51 km/h)55 mph (88.51 km/h)
60 mph (96.56 km/h)59.99 mph (96.55 km/h)
65 mph (104.61 km/h)64.99 mph (104.6 km/h)
70 mph (112.65 km/h)69.99 mph (112.64 km/h)
75 mph (120.7 km/h)74.99 mph (120.69 km/h)
80 mph (128.75 km/h)79.99 mph (128.74 km/h)
85 mph (136.79 km/h)84.99 mph (136.78 km/h)
90 mph (144.84 km/h)89.99 mph (144.83 km/h)
95 mph (152.89 km/h)94.99 mph (152.87 km/h)
100 mph (160.93 km/h)99.99 mph (160.92 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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