Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
305/60r20 vs 33/12.5r20 Tire Comparison Side By Side
  305/60-20 33/12.5-20 Difference
Diameter inches (mm) 34.41 (874) 33.02 (838.72) -1.39 (-35.28) -4%
Width inches (mm) 12.01 (305) 12.52 (318) 0.51 (13) 4.3%
Circum. inches (mm) 108.1 (2745.75) 103.74 (2634.92) -4.36 (-110.84) -4%
Sidewall Height inches (mm) 7.2 (183) 6.51 (165.36) -0.69 (-17.64) -9.6%
Revolutions per mile (km) 586.12 (364.2) 610.78 (379.52) 24.65 (15.32) 4.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.19 mph (30.89 km/h)
25 mph (40.23 km/h)23.99 mph (38.61 km/h)
30 mph (48.28 km/h)28.79 mph (46.33 km/h)
35 mph (56.33 km/h)33.59 mph (54.05 km/h)
40 mph (64.37 km/h)38.39 mph (61.78 km/h)
45 mph (72.42 km/h)43.18 mph (69.5 km/h)
50 mph (80.47 km/h)47.98 mph (77.22 km/h)
55 mph (88.51 km/h)52.78 mph (84.94 km/h)
60 mph (96.56 km/h)57.58 mph (92.66 km/h)
65 mph (104.61 km/h)62.38 mph (100.38 km/h)
70 mph (112.65 km/h)67.17 mph (108.11 km/h)
75 mph (120.7 km/h)71.97 mph (115.83 km/h)
80 mph (128.75 km/h)76.77 mph (123.55 km/h)
85 mph (136.79 km/h)81.57 mph (131.27 km/h)
90 mph (144.84 km/h)86.37 mph (138.99 km/h)
95 mph (152.89 km/h)91.17 mph (146.72 km/h)
100 mph (160.93 km/h)95.96 mph (154.44 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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