Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
120/70r21 vs 110/70r21 Tire Comparison Side By Side
  120/70-21 110/70-21 Difference
Diameter inches (mm) 27.61 (701.4) 27.06 (687.4) -0.55 (-14) -2%
Width inches (mm) 4.72 (120) 4.33 (110) -0.39 (-10) -8.3%
Circum. inches (mm) 86.75 (2203.51) 85.02 (2159.53) -1.73 (-43.98) -2%
Sidewall Height inches (mm) 3.31 (84) 3.03 (77) -0.28 (-7) -8.3%
Revolutions per mile (km) 730.35 (453.82) 745.23 (463.06) 14.87 (9.24) 2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.6 mph (31.54 km/h)
25 mph (40.23 km/h)24.5 mph (39.43 km/h)
30 mph (48.28 km/h)29.4 mph (47.32 km/h)
35 mph (56.33 km/h)34.3 mph (55.2 km/h)
40 mph (64.37 km/h)39.2 mph (63.09 km/h)
45 mph (72.42 km/h)44.1 mph (70.98 km/h)
50 mph (80.47 km/h)49 mph (78.86 km/h)
55 mph (88.51 km/h)53.9 mph (86.75 km/h)
60 mph (96.56 km/h)58.8 mph (94.63 km/h)
65 mph (104.61 km/h)63.7 mph (102.52 km/h)
70 mph (112.65 km/h)68.6 mph (110.41 km/h)
75 mph (120.7 km/h)73.5 mph (118.29 km/h)
80 mph (128.75 km/h)78.4 mph (126.18 km/h)
85 mph (136.79 km/h)83.3 mph (134.06 km/h)
90 mph (144.84 km/h)88.2 mph (141.95 km/h)
95 mph (152.89 km/h)93.1 mph (149.84 km/h)
100 mph (160.93 km/h)98 mph (157.72 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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