Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
120/70r12 vs 100/80r12 Tire Comparison Side By Side
  120/70-12 100/80-12 Difference
Diameter inches (mm) 18.61 (472.8) 18.3 (464.8) -0.31 (-8) -1.7%
Width inches (mm) 4.72 (120) 3.94 (100) -0.79 (-20) -16.7%
Circum. inches (mm) 58.48 (1485.35) 57.49 (1460.21) -0.99 (-25.13) -1.7%
Sidewall Height inches (mm) 3.31 (84) 3.15 (80) -0.16 (-4) -4.8%
Revolutions per mile (km) 1083.48 (673.24) 1102.13 (684.83) 18.65 (11.59) 1.7%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.66 mph (31.64 km/h)
25 mph (40.23 km/h)24.58 mph (39.55 km/h)
30 mph (48.28 km/h)29.49 mph (47.46 km/h)
35 mph (56.33 km/h)34.41 mph (55.37 km/h)
40 mph (64.37 km/h)39.32 mph (63.28 km/h)
45 mph (72.42 km/h)44.24 mph (71.2 km/h)
50 mph (80.47 km/h)49.15 mph (79.11 km/h)
55 mph (88.51 km/h)54.07 mph (87.02 km/h)
60 mph (96.56 km/h)58.98 mph (94.93 km/h)
65 mph (104.61 km/h)63.9 mph (102.84 km/h)
70 mph (112.65 km/h)68.82 mph (110.75 km/h)
75 mph (120.7 km/h)73.73 mph (118.66 km/h)
80 mph (128.75 km/h)78.65 mph (126.57 km/h)
85 mph (136.79 km/h)83.56 mph (134.48 km/h)
90 mph (144.84 km/h)88.48 mph (142.39 km/h)
95 mph (152.89 km/h)93.39 mph (150.3 km/h)
100 mph (160.93 km/h)98.31 mph (158.21 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
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
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