Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
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120/70r12 vs 145/70r12 Tire Comparison Side By Side
  120/70-12 145/70-12 Difference
Diameter inches (mm) 18.61 (472.8) 19.99 (507.8) 1.38 (35) 7.4%
Width inches (mm) 4.72 (120) 5.71 (145) 0.98 (25) 20.8%
Circum. inches (mm) 58.48 (1485.35) 62.81 (1595.3) 4.33 (109.96) 7.4%
Sidewall Height inches (mm) 3.31 (84) 4 (101.5) 0.69 (17.5) 20.8%
Revolutions per mile (km) 1083.48 (673.24) 1008.8 (626.84) -74.68 (-46.4) -6.9%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)21.48 mph (34.57 km/h)
25 mph (40.23 km/h)26.85 mph (43.21 km/h)
30 mph (48.28 km/h)32.22 mph (51.85 km/h)
35 mph (56.33 km/h)37.59 mph (60.5 km/h)
40 mph (64.37 km/h)42.96 mph (69.14 km/h)
45 mph (72.42 km/h)48.33 mph (77.78 km/h)
50 mph (80.47 km/h)53.7 mph (86.42 km/h)
55 mph (88.51 km/h)59.07 mph (95.07 km/h)
60 mph (96.56 km/h)64.44 mph (103.71 km/h)
65 mph (104.61 km/h)69.81 mph (112.35 km/h)
70 mph (112.65 km/h)75.18 mph (120.99 km/h)
75 mph (120.7 km/h)80.55 mph (129.64 km/h)
80 mph (128.75 km/h)85.92 mph (138.28 km/h)
85 mph (136.79 km/h)91.29 mph (146.92 km/h)
90 mph (144.84 km/h)96.66 mph (155.56 km/h)
95 mph (152.89 km/h)102.03 mph (164.21 km/h)
100 mph (160.93 km/h)107.4 mph (172.85 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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