Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
90/80r12 vs 120/70r12 Tire Comparison Side By Side
  90/80-12 120/70-12 Difference
Diameter inches (mm) 17.67 (448.8) 18.61 (472.8) 0.94 (24) 5.3%
Width inches (mm) 3.54 (90) 4.72 (120) 1.18 (30) 33.3%
Circum. inches (mm) 55.51 (1409.95) 58.48 (1485.35) 2.97 (75.4) 5.3%
Sidewall Height inches (mm) 2.83 (72) 3.31 (84) 0.47 (12) 16.7%
Revolutions per mile (km) 1141.42 (709.25) 1083.48 (673.24) -57.94 (-36) -5.1%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)21.07 mph (33.91 km/h)
25 mph (40.23 km/h)26.34 mph (42.39 km/h)
30 mph (48.28 km/h)31.6 mph (50.86 km/h)
35 mph (56.33 km/h)36.87 mph (59.34 km/h)
40 mph (64.37 km/h)42.14 mph (67.82 km/h)
45 mph (72.42 km/h)47.41 mph (76.29 km/h)
50 mph (80.47 km/h)52.67 mph (84.77 km/h)
55 mph (88.51 km/h)57.94 mph (93.25 km/h)
60 mph (96.56 km/h)63.21 mph (101.72 km/h)
65 mph (104.61 km/h)68.48 mph (110.2 km/h)
70 mph (112.65 km/h)73.74 mph (118.68 km/h)
75 mph (120.7 km/h)79.01 mph (127.16 km/h)
80 mph (128.75 km/h)84.28 mph (135.63 km/h)
85 mph (136.79 km/h)89.55 mph (144.11 km/h)
90 mph (144.84 km/h)94.81 mph (152.59 km/h)
95 mph (152.89 km/h)100.08 mph (161.06 km/h)
100 mph (160.93 km/h)105.35 mph (169.54 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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