Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
245/35r21 vs 245/40r20 Tire Comparison Side By Side
  245/35-21 245/40-20 Difference
Diameter inches (mm) 27.75 (704.9) 27.72 (704) -0.04 (-0.9) -0.1%
Width inches (mm) 9.65 (245) 9.65 (245) 0 (0) 0%
Circum. inches (mm) 87.19 (2214.51) 87.07 (2211.68) -0.11 (-2.83) -0.1%
Sidewall Height inches (mm) 3.38 (85.75) 3.86 (98) 0.48 (12.25) 14.3%
Revolutions per mile (km) 726.73 (451.57) 727.66 (452.14) 0.93 (0.58) 0.1%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.97 mph (32.15 km/h)
25 mph (40.23 km/h)24.97 mph (40.18 km/h)
30 mph (48.28 km/h)29.96 mph (48.22 km/h)
35 mph (56.33 km/h)34.96 mph (56.26 km/h)
40 mph (64.37 km/h)39.95 mph (64.29 km/h)
45 mph (72.42 km/h)44.94 mph (72.33 km/h)
50 mph (80.47 km/h)49.94 mph (80.36 km/h)
55 mph (88.51 km/h)54.93 mph (88.4 km/h)
60 mph (96.56 km/h)59.92 mph (96.44 km/h)
65 mph (104.61 km/h)64.92 mph (104.47 km/h)
70 mph (112.65 km/h)69.91 mph (112.51 km/h)
75 mph (120.7 km/h)74.9 mph (120.55 km/h)
80 mph (128.75 km/h)79.9 mph (128.58 km/h)
85 mph (136.79 km/h)84.89 mph (136.62 km/h)
90 mph (144.84 km/h)89.89 mph (144.66 km/h)
95 mph (152.89 km/h)94.88 mph (152.69 km/h)
100 mph (160.93 km/h)99.87 mph (160.73 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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