Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
120/70r18 vs 100/90r18 Tire Comparison Side By Side
  120/70-18 100/90-18 Difference
Diameter inches (mm) 24.61 (625.2) 25.09 (637.2) 0.47 (12) 1.9%
Width inches (mm) 4.72 (120) 3.94 (100) -0.79 (-20) -16.7%
Circum. inches (mm) 77.33 (1964.12) 78.81 (2001.82) 1.48 (37.7) 1.9%
Sidewall Height inches (mm) 3.31 (84) 3.54 (90) 0.24 (6) 7.1%
Revolutions per mile (km) 819.37 (509.13) 803.94 (499.54) -15.43 (-9.59) -1.9%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.38 mph (32.8 km/h)
25 mph (40.23 km/h)25.48 mph (41.01 km/h)
30 mph (48.28 km/h)30.58 mph (49.21 km/h)
35 mph (56.33 km/h)35.67 mph (57.41 km/h)
40 mph (64.37 km/h)40.77 mph (65.61 km/h)
45 mph (72.42 km/h)45.86 mph (73.81 km/h)
50 mph (80.47 km/h)50.96 mph (82.01 km/h)
55 mph (88.51 km/h)56.06 mph (90.21 km/h)
60 mph (96.56 km/h)61.15 mph (98.41 km/h)
65 mph (104.61 km/h)66.25 mph (106.62 km/h)
70 mph (112.65 km/h)71.34 mph (114.82 km/h)
75 mph (120.7 km/h)76.44 mph (123.02 km/h)
80 mph (128.75 km/h)81.54 mph (131.22 km/h)
85 mph (136.79 km/h)86.63 mph (139.42 km/h)
90 mph (144.84 km/h)91.73 mph (147.62 km/h)
95 mph (152.89 km/h)96.82 mph (155.82 km/h)
100 mph (160.93 km/h)101.92 mph (164.02 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
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