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 305/50r20 Tire Comparison Side By Side
  305/55-20 305/50-20 Difference
Diameter inches (mm) 33.21 (843.5) 32.01 (813) -1.2 (-30.5) -3.6%
Width inches (mm) 12.01 (305) 12.01 (305) 0 (0) 0%
Circum. inches (mm) 104.33 (2649.93) 100.56 (2554.11) -3.77 (-95.82) -3.6%
Sidewall Height inches (mm) 6.6 (167.75) 6 (152.5) -0.6 (-15.25) -9.1%
Revolutions per mile (km) 607.31 (377.37) 630.1 (391.52) 22.78 (14.16) 3.8%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.28 mph (31.02 km/h)
25 mph (40.23 km/h)24.1 mph (38.78 km/h)
30 mph (48.28 km/h)28.92 mph (46.53 km/h)
35 mph (56.33 km/h)33.73 mph (54.29 km/h)
40 mph (64.37 km/h)38.55 mph (62.05 km/h)
45 mph (72.42 km/h)43.37 mph (69.8 km/h)
50 mph (80.47 km/h)48.19 mph (77.56 km/h)
55 mph (88.51 km/h)53.01 mph (85.31 km/h)
60 mph (96.56 km/h)57.83 mph (93.07 km/h)
65 mph (104.61 km/h)62.65 mph (100.83 km/h)
70 mph (112.65 km/h)67.47 mph (108.58 km/h)
75 mph (120.7 km/h)72.29 mph (116.34 km/h)
80 mph (128.75 km/h)77.11 mph (124.09 km/h)
85 mph (136.79 km/h)81.93 mph (131.85 km/h)
90 mph (144.84 km/h)86.75 mph (139.6 km/h)
95 mph (152.89 km/h)91.56 mph (147.36 km/h)
100 mph (160.93 km/h)96.38 mph (155.12 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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