Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
305/65r20 vs 305/55r20 Tire Comparison Side By Side
  305/65-20 305/55-20 Difference
Diameter inches (mm) 35.61 (904.5) 33.21 (843.5) -2.4 (-61) -6.7%
Width inches (mm) 12.01 (305) 12.01 (305) 0 (0) 0%
Circum. inches (mm) 111.87 (2841.57) 104.33 (2649.93) -7.54 (-191.64) -6.7%
Sidewall Height inches (mm) 7.81 (198.25) 6.6 (167.75) -1.2 (-30.5) -15.4%
Revolutions per mile (km) 566.36 (351.92) 607.31 (377.37) 40.96 (25.45) 7.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)18.65 mph (30.02 km/h)
25 mph (40.23 km/h)23.31 mph (37.52 km/h)
30 mph (48.28 km/h)27.98 mph (45.02 km/h)
35 mph (56.33 km/h)32.64 mph (52.53 km/h)
40 mph (64.37 km/h)37.3 mph (60.03 km/h)
45 mph (72.42 km/h)41.97 mph (67.54 km/h)
50 mph (80.47 km/h)46.63 mph (75.04 km/h)
55 mph (88.51 km/h)51.29 mph (82.54 km/h)
60 mph (96.56 km/h)55.95 mph (90.05 km/h)
65 mph (104.61 km/h)60.62 mph (97.55 km/h)
70 mph (112.65 km/h)65.28 mph (105.06 km/h)
75 mph (120.7 km/h)69.94 mph (112.56 km/h)
80 mph (128.75 km/h)74.6 mph (120.06 km/h)
85 mph (136.79 km/h)79.27 mph (127.57 km/h)
90 mph (144.84 km/h)83.93 mph (135.07 km/h)
95 mph (152.89 km/h)88.59 mph (142.58 km/h)
100 mph (160.93 km/h)93.26 mph (150.08 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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