Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
285/70r18 vs 33/12.5r18 Tire Comparison Side By Side
  285/70-18 33/12.5-18 Difference
Diameter inches (mm) 33.71 (856.2) 33.02 (838.8) -0.69 (-17.4) -2%
Width inches (mm) 11.22 (285) 12.52 (318) 1.3 (33) 11.6%
Circum. inches (mm) 105.9 (2689.83) 103.75 (2635.17) -2.15 (-54.66) -2%
Sidewall Height inches (mm) 7.85 (199.5) 7.51 (190.8) -0.34 (-8.7) -4.4%
Revolutions per mile (km) 598.31 (371.77) 610.72 (379.48) 12.41 (7.71) 2.1%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.59 mph (31.53 km/h)
25 mph (40.23 km/h)24.49 mph (39.42 km/h)
30 mph (48.28 km/h)29.39 mph (47.3 km/h)
35 mph (56.33 km/h)34.29 mph (55.18 km/h)
40 mph (64.37 km/h)39.19 mph (63.07 km/h)
45 mph (72.42 km/h)44.09 mph (70.95 km/h)
50 mph (80.47 km/h)48.98 mph (78.83 km/h)
55 mph (88.51 km/h)53.88 mph (86.72 km/h)
60 mph (96.56 km/h)58.78 mph (94.6 km/h)
65 mph (104.61 km/h)63.68 mph (102.48 km/h)
70 mph (112.65 km/h)68.58 mph (110.36 km/h)
75 mph (120.7 km/h)73.48 mph (118.25 km/h)
80 mph (128.75 km/h)78.37 mph (126.13 km/h)
85 mph (136.79 km/h)83.27 mph (134.01 km/h)
90 mph (144.84 km/h)88.17 mph (141.9 km/h)
95 mph (152.89 km/h)93.07 mph (149.78 km/h)
100 mph (160.93 km/h)97.97 mph (157.66 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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