Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
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100/80r14 vs 120/70r14 Tire Comparison Side By Side
  100/80-14 120/70-14 Difference
Diameter inches (mm) 20.3 (515.6) 20.61 (523.6) 0.31 (8) 1.6%
Width inches (mm) 3.94 (100) 4.72 (120) 0.79 (20) 20%
Circum. inches (mm) 63.77 (1619.81) 64.76 (1644.94) 0.99 (25.13) 1.6%
Sidewall Height inches (mm) 3.15 (80) 3.31 (84) 0.16 (4) 5%
Revolutions per mile (km) 993.54 (617.36) 978.36 (607.92) -15.18 (-9.43) -1.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.31 mph (32.69 km/h)
25 mph (40.23 km/h)25.39 mph (40.86 km/h)
30 mph (48.28 km/h)30.47 mph (49.03 km/h)
35 mph (56.33 km/h)35.54 mph (57.2 km/h)
40 mph (64.37 km/h)40.62 mph (65.37 km/h)
45 mph (72.42 km/h)45.7 mph (73.54 km/h)
50 mph (80.47 km/h)50.78 mph (81.72 km/h)
55 mph (88.51 km/h)55.85 mph (89.89 km/h)
60 mph (96.56 km/h)60.93 mph (98.06 km/h)
65 mph (104.61 km/h)66.01 mph (106.23 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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