Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
34/12.5r18 vs 285/75r18 Tire Comparison Side By Side
  34/12.5-18 285/75-18 Difference
Diameter inches (mm) 34.03 (864.24) 34.83 (884.7) 0.81 (20.46) 2.4%
Width inches (mm) 12.52 (318) 11.22 (285) -1.3 (-33) -10.4%
Circum. inches (mm) 106.89 (2715.09) 109.42 (2779.37) 2.53 (64.28) 2.4%
Sidewall Height inches (mm) 8.01 (203.52) 8.42 (213.75) 0.4 (10.23) 5%
Revolutions per mile (km) 592.74 (368.31) 579.03 (359.79) -13.71 (-8.52) -2.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.47 mph (32.95 km/h)
25 mph (40.23 km/h)25.59 mph (41.19 km/h)
30 mph (48.28 km/h)30.71 mph (49.42 km/h)
35 mph (56.33 km/h)35.83 mph (57.66 km/h)
40 mph (64.37 km/h)40.95 mph (65.9 km/h)
45 mph (72.42 km/h)46.07 mph (74.14 km/h)
50 mph (80.47 km/h)51.18 mph (82.37 km/h)
55 mph (88.51 km/h)56.3 mph (90.61 km/h)
60 mph (96.56 km/h)61.42 mph (98.85 km/h)
65 mph (104.61 km/h)66.54 mph (107.08 km/h)
70 mph (112.65 km/h)71.66 mph (115.32 km/h)
75 mph (120.7 km/h)76.78 mph (123.56 km/h)
80 mph (128.75 km/h)81.89 mph (131.8 km/h)
85 mph (136.79 km/h)87.01 mph (140.03 km/h)
90 mph (144.84 km/h)92.13 mph (148.27 km/h)
95 mph (152.89 km/h)97.25 mph (156.51 km/h)
100 mph (160.93 km/h)102.37 mph (164.74 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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