Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
325/65r18 vs 35/12.5r18 Tire Comparison Side By Side
  325/65-18 35/12.5-18 Difference
Diameter inches (mm) 34.63 (879.7) 35.03 (889.68) 0.39 (9.98) 1.1%
Width inches (mm) 12.8 (325) 12.52 (318) -0.28 (-7) -2.2%
Circum. inches (mm) 108.81 (2763.66) 110.04 (2795.01) 1.23 (31.35) 1.1%
Sidewall Height inches (mm) 8.32 (211.25) 8.51 (216.24) 0.2 (4.99) 2.4%
Revolutions per mile (km) 582.32 (361.84) 575.79 (357.78) -6.53 (-4.06) -1.1%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.23 mph (32.55 km/h)
25 mph (40.23 km/h)25.28 mph (40.69 km/h)
30 mph (48.28 km/h)30.34 mph (48.83 km/h)
35 mph (56.33 km/h)35.4 mph (56.97 km/h)
40 mph (64.37 km/h)40.45 mph (65.1 km/h)
45 mph (72.42 km/h)45.51 mph (73.24 km/h)
50 mph (80.47 km/h)50.57 mph (81.38 km/h)
55 mph (88.51 km/h)55.62 mph (89.52 km/h)
60 mph (96.56 km/h)60.68 mph (97.66 km/h)
65 mph (104.61 km/h)65.74 mph (105.79 km/h)
70 mph (112.65 km/h)70.79 mph (113.93 km/h)
75 mph (120.7 km/h)75.85 mph (122.07 km/h)
80 mph (128.75 km/h)80.91 mph (130.21 km/h)
85 mph (136.79 km/h)85.96 mph (138.35 km/h)
90 mph (144.84 km/h)91.02 mph (146.48 km/h)
95 mph (152.89 km/h)96.08 mph (154.62 km/h)
100 mph (160.93 km/h)101.13 mph (162.76 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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