Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
305/55r20 vs 285/60r20 Tire Comparison Side By Side
  305/55-20 285/60-20 Difference
Diameter inches (mm) 33.21 (843.5) 33.46 (850) 0.26 (6.5) 0.8%
Width inches (mm) 12.01 (305) 11.22 (285) -0.79 (-20) -6.6%
Circum. inches (mm) 104.33 (2649.93) 105.13 (2670.35) 0.8 (20.42) 0.8%
Sidewall Height inches (mm) 6.6 (167.75) 6.73 (171) 0.13 (3.25) 1.9%
Revolutions per mile (km) 607.31 (377.37) 602.67 (374.48) -4.64 (-2.89) -0.8%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.15 mph (32.43 km/h)
25 mph (40.23 km/h)25.19 mph (40.54 km/h)
30 mph (48.28 km/h)30.23 mph (48.65 km/h)
35 mph (56.33 km/h)35.27 mph (56.76 km/h)
40 mph (64.37 km/h)40.31 mph (64.87 km/h)
45 mph (72.42 km/h)45.35 mph (72.98 km/h)
50 mph (80.47 km/h)50.39 mph (81.09 km/h)
55 mph (88.51 km/h)55.42 mph (89.2 km/h)
60 mph (96.56 km/h)60.46 mph (97.3 km/h)
65 mph (104.61 km/h)65.5 mph (105.41 km/h)
70 mph (112.65 km/h)70.54 mph (113.52 km/h)
75 mph (120.7 km/h)75.58 mph (121.63 km/h)
80 mph (128.75 km/h)80.62 mph (129.74 km/h)
85 mph (136.79 km/h)85.66 mph (137.85 km/h)
90 mph (144.84 km/h)90.69 mph (145.96 km/h)
95 mph (152.89 km/h)95.73 mph (154.07 km/h)
100 mph (160.93 km/h)100.77 mph (162.17 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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