Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
325/60r18 vs 285/70r18 Tire Comparison Side By Side
  325/60-18 285/70-18 Difference
Diameter inches (mm) 33.35 (847.2) 33.71 (856.2) 0.35 (9) 1.1%
Width inches (mm) 12.8 (325) 11.22 (285) -1.57 (-40) -12.3%
Circum. inches (mm) 104.79 (2661.56) 105.9 (2689.83) 1.11 (28.27) 1.1%
Sidewall Height inches (mm) 7.68 (195) 7.85 (199.5) 0.18 (4.5) 2.3%
Revolutions per mile (km) 604.66 (375.72) 598.31 (371.77) -6.36 (-3.95) -1.1%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.21 mph (32.53 km/h)
25 mph (40.23 km/h)25.27 mph (40.66 km/h)
30 mph (48.28 km/h)30.32 mph (48.79 km/h)
35 mph (56.33 km/h)35.37 mph (56.93 km/h)
40 mph (64.37 km/h)40.42 mph (65.06 km/h)
45 mph (72.42 km/h)45.48 mph (73.19 km/h)
50 mph (80.47 km/h)50.53 mph (81.32 km/h)
55 mph (88.51 km/h)55.58 mph (89.45 km/h)
60 mph (96.56 km/h)60.64 mph (97.59 km/h)
65 mph (104.61 km/h)65.69 mph (105.72 km/h)
70 mph (112.65 km/h)70.74 mph (113.85 km/h)
75 mph (120.7 km/h)75.8 mph (121.98 km/h)
80 mph (128.75 km/h)80.85 mph (130.12 km/h)
85 mph (136.79 km/h)85.9 mph (138.25 km/h)
90 mph (144.84 km/h)90.96 mph (146.38 km/h)
95 mph (152.89 km/h)96.01 mph (154.51 km/h)
100 mph (160.93 km/h)101.06 mph (162.64 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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