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 285/60r20 Tire Comparison Side By Side
  305/60-20 285/60-20 Difference
Diameter inches (mm) 34.41 (874) 33.46 (850) -0.94 (-24) -2.7%
Width inches (mm) 12.01 (305) 11.22 (285) -0.79 (-20) -6.6%
Circum. inches (mm) 108.1 (2745.75) 105.13 (2670.35) -2.97 (-75.4) -2.7%
Sidewall Height inches (mm) 7.2 (183) 6.73 (171) -0.47 (-12) -6.6%
Revolutions per mile (km) 586.12 (364.2) 602.67 (374.48) 16.55 (10.28) 2.8%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.45 mph (31.3 km/h)
25 mph (40.23 km/h)24.31 mph (39.13 km/h)
30 mph (48.28 km/h)29.18 mph (46.95 km/h)
35 mph (56.33 km/h)34.04 mph (54.78 km/h)
40 mph (64.37 km/h)38.9 mph (62.61 km/h)
45 mph (72.42 km/h)43.76 mph (70.43 km/h)
50 mph (80.47 km/h)48.63 mph (78.26 km/h)
55 mph (88.51 km/h)53.49 mph (86.08 km/h)
60 mph (96.56 km/h)58.35 mph (93.91 km/h)
65 mph (104.61 km/h)63.22 mph (101.74 km/h)
70 mph (112.65 km/h)68.08 mph (109.56 km/h)
75 mph (120.7 km/h)72.94 mph (117.39 km/h)
80 mph (128.75 km/h)77.8 mph (125.21 km/h)
85 mph (136.79 km/h)82.67 mph (133.04 km/h)
90 mph (144.84 km/h)87.53 mph (140.86 km/h)
95 mph (152.89 km/h)92.39 mph (148.69 km/h)
100 mph (160.93 km/h)97.25 mph (156.52 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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