Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
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275/70r18 vs 325/65r18 Tire Comparison Side By Side
  275/70-18 325/65-18 Difference
Diameter inches (mm) 33.16 (842.2) 34.63 (879.7) 1.48 (37.5) 4.5%
Width inches (mm) 10.83 (275) 12.8 (325) 1.97 (50) 18.2%
Circum. inches (mm) 104.17 (2645.85) 108.81 (2763.66) 4.64 (117.81) 4.5%
Sidewall Height inches (mm) 7.58 (192.5) 8.32 (211.25) 0.74 (18.75) 9.7%
Revolutions per mile (km) 608.25 (377.95) 582.32 (361.84) -25.93 (-16.11) -4.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.89 mph (33.62 km/h)
25 mph (40.23 km/h)26.11 mph (42.03 km/h)
30 mph (48.28 km/h)31.34 mph (50.43 km/h)
35 mph (56.33 km/h)36.56 mph (58.84 km/h)
40 mph (64.37 km/h)41.78 mph (67.24 km/h)
45 mph (72.42 km/h)47 mph (75.65 km/h)
50 mph (80.47 km/h)52.23 mph (84.05 km/h)
55 mph (88.51 km/h)57.45 mph (92.46 km/h)
60 mph (96.56 km/h)62.67 mph (100.86 km/h)
65 mph (104.61 km/h)67.89 mph (109.27 km/h)
70 mph (112.65 km/h)73.12 mph (117.67 km/h)
75 mph (120.7 km/h)78.34 mph (126.08 km/h)
80 mph (128.75 km/h)83.56 mph (134.48 km/h)
85 mph (136.79 km/h)88.78 mph (142.89 km/h)
90 mph (144.84 km/h)94.01 mph (151.29 km/h)
95 mph (152.89 km/h)99.23 mph (159.7 km/h)
100 mph (160.93 km/h)104.45 mph (168.1 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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