Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
215/30r20 vs 215/45r20 Tire Comparison Side By Side
  215/30-20 215/45-20 Difference
Diameter inches (mm) 25.08 (637) 27.62 (701.5) 2.54 (64.5) 10.1%
Width inches (mm) 8.46 (215) 8.46 (215) 0 (0) 0%
Circum. inches (mm) 78.79 (2001.19) 86.76 (2203.83) 7.98 (202.63) 10.1%
Sidewall Height inches (mm) 2.54 (64.5) 3.81 (96.75) 1.27 (32.25) 50%
Revolutions per mile (km) 804.19 (499.7) 730.25 (453.76) -73.94 (-45.95) -9.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)22.03 mph (35.45 km/h)
25 mph (40.23 km/h)27.53 mph (44.31 km/h)
30 mph (48.28 km/h)33.04 mph (53.17 km/h)
35 mph (56.33 km/h)38.54 mph (62.03 km/h)
40 mph (64.37 km/h)44.05 mph (70.89 km/h)
45 mph (72.42 km/h)49.56 mph (79.75 km/h)
50 mph (80.47 km/h)55.06 mph (88.62 km/h)
55 mph (88.51 km/h)60.57 mph (97.48 km/h)
60 mph (96.56 km/h)66.08 mph (106.34 km/h)
65 mph (104.61 km/h)71.58 mph (115.2 km/h)
70 mph (112.65 km/h)77.09 mph (124.06 km/h)
75 mph (120.7 km/h)82.59 mph (132.92 km/h)
80 mph (128.75 km/h)88.1 mph (141.78 km/h)
85 mph (136.79 km/h)93.61 mph (150.65 km/h)
90 mph (144.84 km/h)99.11 mph (159.51 km/h)
95 mph (152.89 km/h)104.62 mph (168.37 km/h)
100 mph (160.93 km/h)110.13 mph (177.23 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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