Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
225/40r18 vs 205/40r18 Tire Comparison Side By Side
  225/40-18 205/40-18 Difference
Diameter inches (mm) 25.09 (637.2) 24.46 (621.2) -0.63 (-16) -2.5%
Width inches (mm) 8.86 (225) 8.07 (205) -0.79 (-20) -8.9%
Circum. inches (mm) 78.81 (2001.82) 76.83 (1951.56) -1.98 (-50.27) -2.5%
Sidewall Height inches (mm) 3.54 (90) 3.23 (82) -0.31 (-8) -8.9%
Revolutions per mile (km) 803.94 (499.54) 824.65 (512.41) 20.71 (12.87) 2.6%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.5 mph (31.38 km/h)
25 mph (40.23 km/h)24.37 mph (39.22 km/h)
30 mph (48.28 km/h)29.25 mph (47.07 km/h)
35 mph (56.33 km/h)34.12 mph (54.91 km/h)
40 mph (64.37 km/h)39 mph (62.76 km/h)
45 mph (72.42 km/h)43.87 mph (70.6 km/h)
50 mph (80.47 km/h)48.74 mph (78.45 km/h)
55 mph (88.51 km/h)53.62 mph (86.29 km/h)
60 mph (96.56 km/h)58.49 mph (94.14 km/h)
65 mph (104.61 km/h)63.37 mph (101.98 km/h)
70 mph (112.65 km/h)68.24 mph (109.83 km/h)
75 mph (120.7 km/h)73.12 mph (117.67 km/h)
80 mph (128.75 km/h)77.99 mph (125.51 km/h)
85 mph (136.79 km/h)82.87 mph (133.36 km/h)
90 mph (144.84 km/h)87.74 mph (141.2 km/h)
95 mph (152.89 km/h)92.61 mph (149.05 km/h)
100 mph (160.93 km/h)97.49 mph (156.89 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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