Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
315/75r18 vs 37/12.5r18 Tire Comparison Side By Side
  315/75-18 37/12.5-18 Difference
Diameter inches (mm) 36.6 (929.7) 37.03 (940.56) 0.43 (10.86) 1.2%
Width inches (mm) 12.4 (315) 12.52 (318) 0.12 (3) 1%
Circum. inches (mm) 114.99 (2920.74) 116.33 (2954.86) 1.34 (34.12) 1.2%
Sidewall Height inches (mm) 9.3 (236.25) 9.51 (241.68) 0.21 (5.43) 2.3%
Revolutions per mile (km) 551.01 (342.38) 544.64 (338.43) -6.36 (-3.95) -1.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.23 mph (32.56 km/h)
25 mph (40.23 km/h)25.29 mph (40.7 km/h)
30 mph (48.28 km/h)30.35 mph (48.84 km/h)
35 mph (56.33 km/h)35.41 mph (56.99 km/h)
40 mph (64.37 km/h)40.47 mph (65.13 km/h)
45 mph (72.42 km/h)45.53 mph (73.27 km/h)
50 mph (80.47 km/h)50.58 mph (81.41 km/h)
55 mph (88.51 km/h)55.64 mph (89.55 km/h)
60 mph (96.56 km/h)60.7 mph (97.69 km/h)
65 mph (104.61 km/h)65.76 mph (105.83 km/h)
70 mph (112.65 km/h)70.82 mph (113.97 km/h)
75 mph (120.7 km/h)75.88 mph (122.11 km/h)
80 mph (128.75 km/h)80.93 mph (130.25 km/h)
85 mph (136.79 km/h)85.99 mph (138.39 km/h)
90 mph (144.84 km/h)91.05 mph (146.53 km/h)
95 mph (152.89 km/h)96.11 mph (154.67 km/h)
100 mph (160.93 km/h)101.17 mph (162.81 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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