Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
245/40r20 vs 245/35r21 Tire Comparison Side By Side
  245/40-20 245/35-21 Difference
Diameter inches (mm) 27.72 (704) 27.75 (704.9) 0.04 (0.9) 0.1%
Width inches (mm) 9.65 (245) 9.65 (245) 0 (0) 0%
Circum. inches (mm) 87.07 (2211.68) 87.19 (2214.51) 0.11 (2.83) 0.1%
Sidewall Height inches (mm) 3.86 (98) 3.38 (85.75) -0.48 (-12.25) -12.5%
Revolutions per mile (km) 727.66 (452.14) 726.73 (451.57) -0.93 (-0.58) -0.1%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.03 mph (32.23 km/h)
25 mph (40.23 km/h)25.03 mph (40.29 km/h)
30 mph (48.28 km/h)30.04 mph (48.34 km/h)
35 mph (56.33 km/h)35.04 mph (56.4 km/h)
40 mph (64.37 km/h)40.05 mph (64.46 km/h)
45 mph (72.42 km/h)45.06 mph (72.51 km/h)
50 mph (80.47 km/h)50.06 mph (80.57 km/h)
55 mph (88.51 km/h)55.07 mph (88.63 km/h)
60 mph (96.56 km/h)60.08 mph (96.68 km/h)
65 mph (104.61 km/h)65.08 mph (104.74 km/h)
70 mph (112.65 km/h)70.09 mph (112.8 km/h)
75 mph (120.7 km/h)75.1 mph (120.86 km/h)
80 mph (128.75 km/h)80.1 mph (128.91 km/h)
85 mph (136.79 km/h)85.11 mph (136.97 km/h)
90 mph (144.84 km/h)90.12 mph (145.03 km/h)
95 mph (152.89 km/h)95.12 mph (153.08 km/h)
100 mph (160.93 km/h)100.13 mph (161.14 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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