Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
225/45r18 vs 225/40r18 Tire Comparison Side By Side
  225/45-18 225/40-18 Difference
Diameter inches (mm) 25.97 (659.7) 25.09 (637.2) -0.89 (-22.5) -3.4%
Width inches (mm) 8.86 (225) 8.86 (225) 0 (0) 0%
Circum. inches (mm) 81.59 (2072.51) 78.81 (2001.82) -2.78 (-70.69) -3.4%
Sidewall Height inches (mm) 3.99 (101.25) 3.54 (90) -0.44 (-11.25) -11.1%
Revolutions per mile (km) 776.52 (482.51) 803.94 (499.54) 27.42 (17.04) 3.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.32 mph (31.09 km/h)
25 mph (40.23 km/h)24.15 mph (38.86 km/h)
30 mph (48.28 km/h)28.98 mph (46.63 km/h)
35 mph (56.33 km/h)33.81 mph (54.41 km/h)
40 mph (64.37 km/h)38.64 mph (62.18 km/h)
45 mph (72.42 km/h)43.47 mph (69.95 km/h)
50 mph (80.47 km/h)48.29 mph (77.72 km/h)
55 mph (88.51 km/h)53.12 mph (85.5 km/h)
60 mph (96.56 km/h)57.95 mph (93.27 km/h)
65 mph (104.61 km/h)62.78 mph (101.04 km/h)
70 mph (112.65 km/h)67.61 mph (108.81 km/h)
75 mph (120.7 km/h)72.44 mph (116.58 km/h)
80 mph (128.75 km/h)77.27 mph (124.36 km/h)
85 mph (136.79 km/h)82.1 mph (132.13 km/h)
90 mph (144.84 km/h)86.93 mph (139.9 km/h)
95 mph (152.89 km/h)91.76 mph (147.67 km/h)
100 mph (160.93 km/h)96.59 mph (155.45 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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