Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
325/60r20 vs 305/55r20 Tire Comparison Side By Side
  325/60-20 305/55-20 Difference
Diameter inches (mm) 35.35 (898) 33.21 (843.5) -2.15 (-54.5) -6.1%
Width inches (mm) 12.8 (325) 12.01 (305) -0.79 (-20) -6.2%
Circum. inches (mm) 111.07 (2821.15) 104.33 (2649.93) -6.74 (-171.22) -6.1%
Sidewall Height inches (mm) 7.68 (195) 6.6 (167.75) -1.07 (-27.25) -14%
Revolutions per mile (km) 570.46 (354.46) 607.31 (377.37) 36.86 (22.9) 6.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)18.79 mph (30.23 km/h)
25 mph (40.23 km/h)23.48 mph (37.79 km/h)
30 mph (48.28 km/h)28.18 mph (45.35 km/h)
35 mph (56.33 km/h)32.88 mph (52.91 km/h)
40 mph (64.37 km/h)37.57 mph (60.47 km/h)
45 mph (72.42 km/h)42.27 mph (68.03 km/h)
50 mph (80.47 km/h)46.97 mph (75.58 km/h)
55 mph (88.51 km/h)51.66 mph (83.14 km/h)
60 mph (96.56 km/h)56.36 mph (90.7 km/h)
65 mph (104.61 km/h)61.06 mph (98.26 km/h)
70 mph (112.65 km/h)65.75 mph (105.82 km/h)
75 mph (120.7 km/h)70.45 mph (113.38 km/h)
80 mph (128.75 km/h)75.14 mph (120.93 km/h)
85 mph (136.79 km/h)79.84 mph (128.49 km/h)
90 mph (144.84 km/h)84.54 mph (136.05 km/h)
95 mph (152.89 km/h)89.23 mph (143.61 km/h)
100 mph (160.93 km/h)93.93 mph (151.17 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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