Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
305/45r20 vs 285/50r20 Tire Comparison Side By Side
  305/45-20 285/50-20 Difference
Diameter inches (mm) 30.81 (782.5) 31.22 (793) 0.41 (10.5) 1.3%
Width inches (mm) 12.01 (305) 11.22 (285) -0.79 (-20) -6.6%
Circum. inches (mm) 96.78 (2458.3) 98.08 (2491.28) 1.3 (32.99) 1.3%
Sidewall Height inches (mm) 5.4 (137.25) 5.61 (142.5) 0.21 (5.25) 3.8%
Revolutions per mile (km) 654.66 (406.79) 645.99 (401.4) -8.67 (-5.39) -1.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.27 mph (32.62 km/h)
25 mph (40.23 km/h)25.34 mph (40.77 km/h)
30 mph (48.28 km/h)30.4 mph (48.93 km/h)
35 mph (56.33 km/h)35.47 mph (57.08 km/h)
40 mph (64.37 km/h)40.54 mph (65.24 km/h)
45 mph (72.42 km/h)45.6 mph (73.39 km/h)
50 mph (80.47 km/h)50.67 mph (81.55 km/h)
55 mph (88.51 km/h)55.74 mph (89.7 km/h)
60 mph (96.56 km/h)60.81 mph (97.86 km/h)
65 mph (104.61 km/h)65.87 mph (106.01 km/h)
70 mph (112.65 km/h)70.94 mph (114.17 km/h)
75 mph (120.7 km/h)76.01 mph (122.32 km/h)
80 mph (128.75 km/h)81.07 mph (130.48 km/h)
85 mph (136.79 km/h)86.14 mph (138.63 km/h)
90 mph (144.84 km/h)91.21 mph (146.78 km/h)
95 mph (152.89 km/h)96.27 mph (154.94 km/h)
100 mph (160.93 km/h)101.34 mph (163.09 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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