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 285/55r20 Tire Comparison Side By Side
  305/55-20 285/55-20 Difference
Diameter inches (mm) 33.21 (843.5) 32.34 (821.5) -0.87 (-22) -2.6%
Width inches (mm) 12.01 (305) 11.22 (285) -0.79 (-20) -6.6%
Circum. inches (mm) 104.33 (2649.93) 101.61 (2580.82) -2.72 (-69.12) -2.6%
Sidewall Height inches (mm) 6.6 (167.75) 6.17 (156.75) -0.43 (-11) -6.6%
Revolutions per mile (km) 607.31 (377.37) 623.58 (387.47) 16.26 (10.11) 2.7%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.48 mph (31.35 km/h)
25 mph (40.23 km/h)24.35 mph (39.18 km/h)
30 mph (48.28 km/h)29.22 mph (47.02 km/h)
35 mph (56.33 km/h)34.09 mph (54.86 km/h)
40 mph (64.37 km/h)38.96 mph (62.69 km/h)
45 mph (72.42 km/h)43.83 mph (70.53 km/h)
50 mph (80.47 km/h)48.7 mph (78.37 km/h)
55 mph (88.51 km/h)53.57 mph (86.21 km/h)
60 mph (96.56 km/h)58.44 mph (94.04 km/h)
65 mph (104.61 km/h)63.3 mph (101.88 km/h)
70 mph (112.65 km/h)68.17 mph (109.72 km/h)
75 mph (120.7 km/h)73.04 mph (117.55 km/h)
80 mph (128.75 km/h)77.91 mph (125.39 km/h)
85 mph (136.79 km/h)82.78 mph (133.23 km/h)
90 mph (144.84 km/h)87.65 mph (141.06 km/h)
95 mph (152.89 km/h)92.52 mph (148.9 km/h)
100 mph (160.93 km/h)97.39 mph (156.74 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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