Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
245/40r18 vs 235/45r18 Tire Comparison Side By Side
  245/40-18 235/45-18 Difference
Diameter inches (mm) 25.72 (653.2) 26.33 (668.7) 0.61 (15.5) 2.4%
Width inches (mm) 9.65 (245) 9.25 (235) -0.39 (-10) -4.1%
Circum. inches (mm) 80.79 (2052.09) 82.71 (2100.78) 1.92 (48.69) 2.4%
Sidewall Height inches (mm) 3.86 (98) 4.16 (105.75) 0.31 (7.75) 7.9%
Revolutions per mile (km) 784.25 (487.31) 766.07 (476.01) -18.18 (-11.3) -2.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.47 mph (32.95 km/h)
25 mph (40.23 km/h)25.59 mph (41.19 km/h)
30 mph (48.28 km/h)30.71 mph (49.43 km/h)
35 mph (56.33 km/h)35.83 mph (57.66 km/h)
40 mph (64.37 km/h)40.95 mph (65.9 km/h)
45 mph (72.42 km/h)46.07 mph (74.14 km/h)
50 mph (80.47 km/h)51.19 mph (82.38 km/h)
55 mph (88.51 km/h)56.31 mph (90.61 km/h)
60 mph (96.56 km/h)61.42 mph (98.85 km/h)
65 mph (104.61 km/h)66.54 mph (107.09 km/h)
70 mph (112.65 km/h)71.66 mph (115.33 km/h)
75 mph (120.7 km/h)76.78 mph (123.57 km/h)
80 mph (128.75 km/h)81.9 mph (131.8 km/h)
85 mph (136.79 km/h)87.02 mph (140.04 km/h)
90 mph (144.84 km/h)92.14 mph (148.28 km/h)
95 mph (152.89 km/h)97.25 mph (156.52 km/h)
100 mph (160.93 km/h)102.37 mph (164.75 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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