Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
305/45r20 vs 315/50r20 Tire Comparison Side By Side
  305/45-20 315/50-20 Difference
Diameter inches (mm) 30.81 (782.5) 32.4 (823) 1.59 (40.5) 5.2%
Width inches (mm) 12.01 (305) 12.4 (315) 0.39 (10) 3.3%
Circum. inches (mm) 96.78 (2458.3) 101.79 (2585.53) 5.01 (127.23) 5.2%
Sidewall Height inches (mm) 5.4 (137.25) 6.2 (157.5) 0.8 (20.25) 14.8%
Revolutions per mile (km) 654.66 (406.79) 622.44 (386.77) -32.22 (-20.02) -4.9%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)21.04 mph (33.85 km/h)
25 mph (40.23 km/h)26.29 mph (42.32 km/h)
30 mph (48.28 km/h)31.55 mph (50.78 km/h)
35 mph (56.33 km/h)36.81 mph (59.24 km/h)
40 mph (64.37 km/h)42.07 mph (67.71 km/h)
45 mph (72.42 km/h)47.33 mph (76.17 km/h)
50 mph (80.47 km/h)52.59 mph (84.63 km/h)
55 mph (88.51 km/h)57.85 mph (93.1 km/h)
60 mph (96.56 km/h)63.11 mph (101.56 km/h)
65 mph (104.61 km/h)68.36 mph (110.02 km/h)
70 mph (112.65 km/h)73.62 mph (118.48 km/h)
75 mph (120.7 km/h)78.88 mph (126.95 km/h)
80 mph (128.75 km/h)84.14 mph (135.41 km/h)
85 mph (136.79 km/h)89.4 mph (143.87 km/h)
90 mph (144.84 km/h)94.66 mph (152.34 km/h)
95 mph (152.89 km/h)99.92 mph (160.8 km/h)
100 mph (160.93 km/h)105.18 mph (169.26 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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