Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
225/45r17 vs 225/40r18 Tire Comparison Side By Side
  225/45-17 225/40-18 Difference
Diameter inches (mm) 24.97 (634.3) 25.09 (637.2) 0.11 (2.9) 0.5%
Width inches (mm) 8.86 (225) 8.86 (225) 0 (0) 0%
Circum. inches (mm) 78.45 (1992.71) 78.81 (2001.82) 0.36 (9.11) 0.5%
Sidewall Height inches (mm) 3.99 (101.25) 3.54 (90) -0.44 (-11.25) -11.1%
Revolutions per mile (km) 807.61 (501.83) 803.94 (499.54) -3.68 (-2.28) -0.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.09 mph (32.33 km/h)
25 mph (40.23 km/h)25.11 mph (40.42 km/h)
30 mph (48.28 km/h)30.14 mph (48.5 km/h)
35 mph (56.33 km/h)35.16 mph (56.58 km/h)
40 mph (64.37 km/h)40.18 mph (64.67 km/h)
45 mph (72.42 km/h)45.21 mph (72.75 km/h)
50 mph (80.47 km/h)50.23 mph (80.84 km/h)
55 mph (88.51 km/h)55.25 mph (88.92 km/h)
60 mph (96.56 km/h)60.27 mph (97 km/h)
65 mph (104.61 km/h)65.3 mph (105.09 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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