Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
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325/40r18 vs 265/35r18 Tire Comparison Side By Side
  325/40-18 265/35-18 Difference
Diameter inches (mm) 28.24 (717.2) 25.3 (642.7) -2.93 (-74.5) -10.4%
Width inches (mm) 12.8 (325) 10.43 (265) -2.36 (-60) -18.5%
Circum. inches (mm) 88.71 (2253.15) 79.49 (2019.1) -9.21 (-234.05) -10.4%
Sidewall Height inches (mm) 5.12 (130) 3.65 (92.75) -1.47 (-37.25) -28.7%
Revolutions per mile (km) 714.26 (443.82) 797.06 (495.27) 82.8 (51.45) 11.6%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)17.92 mph (28.84 km/h)
25 mph (40.23 km/h)22.4 mph (36.05 km/h)
30 mph (48.28 km/h)26.88 mph (43.27 km/h)
35 mph (56.33 km/h)31.36 mph (50.48 km/h)
40 mph (64.37 km/h)35.84 mph (57.69 km/h)
45 mph (72.42 km/h)40.33 mph (64.9 km/h)
50 mph (80.47 km/h)44.81 mph (72.11 km/h)
55 mph (88.51 km/h)49.29 mph (79.32 km/h)
60 mph (96.56 km/h)53.77 mph (86.53 km/h)
65 mph (104.61 km/h)58.25 mph (93.74 km/h)
70 mph (112.65 km/h)62.73 mph (100.95 km/h)
75 mph (120.7 km/h)67.21 mph (108.16 km/h)
80 mph (128.75 km/h)71.69 mph (115.37 km/h)
85 mph (136.79 km/h)76.17 mph (122.58 km/h)
90 mph (144.84 km/h)80.65 mph (129.8 km/h)
95 mph (152.89 km/h)85.13 mph (137.01 km/h)
100 mph (160.93 km/h)89.61 mph (144.22 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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