Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
180/60r18 vs 185/60r18 Tire Comparison Side By Side
  180/60-18 185/60-18 Difference
Diameter inches (mm) 26.5 (673.2) 26.74 (679.2) 0.24 (6) 0.9%
Width inches (mm) 7.09 (180) 7.28 (185) 0.2 (5) 2.8%
Circum. inches (mm) 83.26 (2114.92) 84.01 (2133.77) 0.74 (18.85) 0.9%
Sidewall Height inches (mm) 4.25 (108) 4.37 (111) 0.12 (3) 2.8%
Revolutions per mile (km) 760.95 (472.83) 754.23 (468.65) -6.72 (-4.18) -0.9%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.18 mph (32.47 km/h)
25 mph (40.23 km/h)25.22 mph (40.59 km/h)
30 mph (48.28 km/h)30.27 mph (48.71 km/h)
35 mph (56.33 km/h)35.31 mph (56.83 km/h)
40 mph (64.37 km/h)40.36 mph (64.95 km/h)
45 mph (72.42 km/h)45.4 mph (73.07 km/h)
50 mph (80.47 km/h)50.45 mph (81.18 km/h)
55 mph (88.51 km/h)55.49 mph (89.3 km/h)
60 mph (96.56 km/h)60.53 mph (97.42 km/h)
65 mph (104.61 km/h)65.58 mph (105.54 km/h)
70 mph (112.65 km/h)70.62 mph (113.66 km/h)
75 mph (120.7 km/h)75.67 mph (121.78 km/h)
80 mph (128.75 km/h)80.71 mph (129.9 km/h)
85 mph (136.79 km/h)85.76 mph (138.01 km/h)
90 mph (144.84 km/h)90.8 mph (146.13 km/h)
95 mph (152.89 km/h)95.85 mph (154.25 km/h)
100 mph (160.93 km/h)100.89 mph (162.37 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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