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 235/40r18 Tire Comparison Side By Side
  225/45-17 235/40-18 Difference
Diameter inches (mm) 24.97 (634.3) 25.4 (645.2) 0.43 (10.9) 1.7%
Width inches (mm) 8.86 (225) 9.25 (235) 0.39 (10) 4.4%
Circum. inches (mm) 78.45 (1992.71) 79.8 (2026.96) 1.35 (34.24) 1.7%
Sidewall Height inches (mm) 3.99 (101.25) 3.7 (94) -0.29 (-7.25) -7.2%
Revolutions per mile (km) 807.61 (501.83) 793.97 (493.35) -13.64 (-8.48) -1.7%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.34 mph (32.74 km/h)
25 mph (40.23 km/h)25.43 mph (40.93 km/h)
30 mph (48.28 km/h)30.52 mph (49.11 km/h)
35 mph (56.33 km/h)35.6 mph (57.3 km/h)
40 mph (64.37 km/h)40.69 mph (65.48 km/h)
45 mph (72.42 km/h)45.77 mph (73.67 km/h)
50 mph (80.47 km/h)50.86 mph (81.85 km/h)
55 mph (88.51 km/h)55.95 mph (90.04 km/h)
60 mph (96.56 km/h)61.03 mph (98.22 km/h)
65 mph (104.61 km/h)66.12 mph (106.41 km/h)
70 mph (112.65 km/h)71.2 mph (114.59 km/h)
75 mph (120.7 km/h)76.29 mph (122.78 km/h)
80 mph (128.75 km/h)81.37 mph (130.96 km/h)
85 mph (136.79 km/h)86.46 mph (139.15 km/h)
90 mph (144.84 km/h)91.55 mph (147.33 km/h)
95 mph (152.89 km/h)96.63 mph (155.52 km/h)
100 mph (160.93 km/h)101.72 mph (163.7 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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