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 315/75r18 Tire Comparison Side By Side
  37/12.5-18 315/75-18 Difference
Diameter inches (mm) 37.03 (940.56) 36.6 (929.7) -0.43 (-10.86) -1.2%
Width inches (mm) 12.52 (318) 12.4 (315) -0.12 (-3) -0.9%
Circum. inches (mm) 116.33 (2954.86) 114.99 (2920.74) -1.34 (-34.12) -1.2%
Sidewall Height inches (mm) 9.51 (241.68) 9.3 (236.25) -0.21 (-5.43) -2.2%
Revolutions per mile (km) 544.64 (338.43) 551.01 (342.38) 6.36 (3.95) 1.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.77 mph (31.82 km/h)
25 mph (40.23 km/h)24.71 mph (39.77 km/h)
30 mph (48.28 km/h)29.65 mph (47.72 km/h)
35 mph (56.33 km/h)34.6 mph (55.68 km/h)
40 mph (64.37 km/h)39.54 mph (63.63 km/h)
45 mph (72.42 km/h)44.48 mph (71.58 km/h)
50 mph (80.47 km/h)49.42 mph (79.54 km/h)
55 mph (88.51 km/h)54.36 mph (87.49 km/h)
60 mph (96.56 km/h)59.31 mph (95.45 km/h)
65 mph (104.61 km/h)64.25 mph (103.4 km/h)
70 mph (112.65 km/h)69.19 mph (111.35 km/h)
75 mph (120.7 km/h)74.13 mph (119.31 km/h)
80 mph (128.75 km/h)79.08 mph (127.26 km/h)
85 mph (136.79 km/h)84.02 mph (135.22 km/h)
90 mph (144.84 km/h)88.96 mph (143.17 km/h)
95 mph (152.89 km/h)93.9 mph (151.12 km/h)
100 mph (160.93 km/h)98.85 mph (159.08 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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