Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
90/90r21 vs 140/80r18 Tire Comparison Side By Side
  90/90-21 140/80-18 Difference
Diameter inches (mm) 27.38 (695.4) 26.82 (681.2) -0.56 (-14.2) -2%
Width inches (mm) 3.54 (90) 5.51 (140) 1.97 (50) 55.6%
Circum. inches (mm) 86.01 (2184.66) 84.25 (2140.05) -1.76 (-44.61) -2%
Sidewall Height inches (mm) 3.19 (81) 4.41 (112) 1.22 (31) 38.3%
Revolutions per mile (km) 736.66 (457.74) 752.01 (467.28) 15.36 (9.54) 2.1%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.59 mph (31.53 km/h)
25 mph (40.23 km/h)24.49 mph (39.41 km/h)
30 mph (48.28 km/h)29.39 mph (47.29 km/h)
35 mph (56.33 km/h)34.29 mph (55.18 km/h)
40 mph (64.37 km/h)39.18 mph (63.06 km/h)
45 mph (72.42 km/h)44.08 mph (70.94 km/h)
50 mph (80.47 km/h)48.98 mph (78.82 km/h)
55 mph (88.51 km/h)53.88 mph (86.71 km/h)
60 mph (96.56 km/h)58.77 mph (94.59 km/h)
65 mph (104.61 km/h)63.67 mph (102.47 km/h)
70 mph (112.65 km/h)68.57 mph (110.35 km/h)
75 mph (120.7 km/h)73.47 mph (118.24 km/h)
80 mph (128.75 km/h)78.37 mph (126.12 km/h)
85 mph (136.79 km/h)83.26 mph (134 km/h)
90 mph (144.84 km/h)88.16 mph (141.88 km/h)
95 mph (152.89 km/h)93.06 mph (149.77 km/h)
100 mph (160.93 km/h)97.96 mph (157.65 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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