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 100/60r12 Tire Comparison Side By Side
  120/70-12 100/60-12 Difference
Diameter inches (mm) 18.61 (472.8) 16.72 (424.8) -1.89 (-48) -10.2%
Width inches (mm) 4.72 (120) 3.94 (100) -0.79 (-20) -16.7%
Circum. inches (mm) 58.48 (1485.35) 52.54 (1334.55) -5.94 (-150.8) -10.2%
Sidewall Height inches (mm) 3.31 (84) 2.36 (60) -0.94 (-24) -28.6%
Revolutions per mile (km) 1083.48 (673.24) 1205.91 (749.32) 122.43 (76.07) 11.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)17.97 mph (28.92 km/h)
25 mph (40.23 km/h)22.46 mph (36.15 km/h)
30 mph (48.28 km/h)26.95 mph (43.38 km/h)
35 mph (56.33 km/h)31.45 mph (50.61 km/h)
40 mph (64.37 km/h)35.94 mph (57.84 km/h)
45 mph (72.42 km/h)40.43 mph (65.07 km/h)
50 mph (80.47 km/h)44.92 mph (72.3 km/h)
55 mph (88.51 km/h)49.42 mph (79.53 km/h)
60 mph (96.56 km/h)53.91 mph (86.76 km/h)
65 mph (104.61 km/h)58.4 mph (93.99 km/h)
70 mph (112.65 km/h)62.89 mph (101.22 km/h)
75 mph (120.7 km/h)67.39 mph (108.45 km/h)
80 mph (128.75 km/h)71.88 mph (115.68 km/h)
85 mph (136.79 km/h)76.37 mph (122.91 km/h)
90 mph (144.84 km/h)80.86 mph (130.14 km/h)
95 mph (152.89 km/h)85.36 mph (137.37 km/h)
100 mph (160.93 km/h)89.85 mph (144.6 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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