Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
245/30r21 vs 235/35r20 Tire Comparison Side By Side
  245/30-21 235/35-20 Difference
Diameter inches (mm) 26.79 (680.4) 26.48 (672.5) -0.31 (-7.9) -1.2%
Width inches (mm) 9.65 (245) 9.25 (235) -0.39 (-10) -4.1%
Circum. inches (mm) 84.16 (2137.54) 83.18 (2112.72) -0.98 (-24.82) -1.2%
Sidewall Height inches (mm) 2.89 (73.5) 3.24 (82.25) 0.34 (8.75) 11.9%
Revolutions per mile (km) 752.9 (467.83) 761.74 (473.32) 8.84 (5.5) 1.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.77 mph (31.81 km/h)
25 mph (40.23 km/h)24.71 mph (39.77 km/h)
30 mph (48.28 km/h)29.65 mph (47.72 km/h)
35 mph (56.33 km/h)34.59 mph (55.67 km/h)
40 mph (64.37 km/h)39.54 mph (63.63 km/h)
45 mph (72.42 km/h)44.48 mph (71.58 km/h)
50 mph (80.47 km/h)49.42 mph (79.53 km/h)
55 mph (88.51 km/h)54.36 mph (87.49 km/h)
60 mph (96.56 km/h)59.3 mph (95.44 km/h)
65 mph (104.61 km/h)64.25 mph (103.39 km/h)
70 mph (112.65 km/h)69.19 mph (111.35 km/h)
75 mph (120.7 km/h)74.13 mph (119.3 km/h)
80 mph (128.75 km/h)79.07 mph (127.25 km/h)
85 mph (136.79 km/h)84.01 mph (135.21 km/h)
90 mph (144.84 km/h)88.96 mph (143.16 km/h)
95 mph (152.89 km/h)93.9 mph (151.11 km/h)
100 mph (160.93 km/h)98.84 mph (159.07 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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