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 215/25r20 Tire Comparison Side By Side
  215/30-20 215/25-20 Difference
Diameter inches (mm) 25.08 (637) 24.23 (615.5) -0.85 (-21.5) -3.4%
Width inches (mm) 8.46 (215) 8.46 (215) 0 (0) 0%
Circum. inches (mm) 78.79 (2001.19) 76.13 (1933.65) -2.66 (-67.54) -3.4%
Sidewall Height inches (mm) 2.54 (64.5) 2.12 (53.75) -0.42 (-10.75) -16.7%
Revolutions per mile (km) 804.19 (499.7) 832.28 (517.16) 28.09 (17.46) 3.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.32 mph (31.1 km/h)
25 mph (40.23 km/h)24.16 mph (38.88 km/h)
30 mph (48.28 km/h)28.99 mph (46.65 km/h)
35 mph (56.33 km/h)33.82 mph (54.43 km/h)
40 mph (64.37 km/h)38.65 mph (62.2 km/h)
45 mph (72.42 km/h)43.48 mph (69.98 km/h)
50 mph (80.47 km/h)48.31 mph (77.75 km/h)
55 mph (88.51 km/h)53.14 mph (85.53 km/h)
60 mph (96.56 km/h)57.97 mph (93.3 km/h)
65 mph (104.61 km/h)62.81 mph (101.08 km/h)
70 mph (112.65 km/h)67.64 mph (108.85 km/h)
75 mph (120.7 km/h)72.47 mph (116.63 km/h)
80 mph (128.75 km/h)77.3 mph (124.4 km/h)
85 mph (136.79 km/h)82.13 mph (132.18 km/h)
90 mph (144.84 km/h)86.96 mph (139.95 km/h)
95 mph (152.89 km/h)91.79 mph (147.73 km/h)
100 mph (160.93 km/h)96.62 mph (155.5 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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