Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
285/55r18 vs 305/65r18 Tire Comparison Side By Side
  285/55-18 305/65-18 Difference
Diameter inches (mm) 30.34 (770.7) 33.61 (853.7) 3.27 (83) 10.8%
Width inches (mm) 11.22 (285) 12.01 (305) 0.79 (20) 7%
Circum. inches (mm) 95.32 (2421.23) 105.59 (2681.98) 10.27 (260.75) 10.8%
Sidewall Height inches (mm) 6.17 (156.75) 7.81 (198.25) 1.63 (41.5) 26.5%
Revolutions per mile (km) 664.68 (413.01) 600.06 (372.86) -64.62 (-40.15) -9.7%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)22.15 mph (35.65 km/h)
25 mph (40.23 km/h)27.69 mph (44.57 km/h)
30 mph (48.28 km/h)33.23 mph (53.48 km/h)
35 mph (56.33 km/h)38.77 mph (62.39 km/h)
40 mph (64.37 km/h)44.31 mph (71.31 km/h)
45 mph (72.42 km/h)49.85 mph (80.22 km/h)
50 mph (80.47 km/h)55.38 mph (89.13 km/h)
55 mph (88.51 km/h)60.92 mph (98.05 km/h)
60 mph (96.56 km/h)66.46 mph (106.96 km/h)
65 mph (104.61 km/h)72 mph (115.87 km/h)
70 mph (112.65 km/h)77.54 mph (124.79 km/h)
75 mph (120.7 km/h)83.08 mph (133.7 km/h)
80 mph (128.75 km/h)88.62 mph (142.61 km/h)
85 mph (136.79 km/h)94.15 mph (151.53 km/h)
90 mph (144.84 km/h)99.69 mph (160.44 km/h)
95 mph (152.89 km/h)105.23 mph (169.35 km/h)
100 mph (160.93 km/h)110.77 mph (178.27 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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