Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
315/75r18 vs 305/75r18 Tire Comparison Side By Side
  315/75-18 305/75-18 Difference
Diameter inches (mm) 36.6 (929.7) 36.01 (914.7) -0.59 (-15) -1.6%
Width inches (mm) 12.4 (315) 12.01 (305) -0.39 (-10) -3.2%
Circum. inches (mm) 114.99 (2920.74) 113.13 (2873.61) -1.86 (-47.12) -1.6%
Sidewall Height inches (mm) 9.3 (236.25) 9.01 (228.75) -0.3 (-7.5) -3.2%
Revolutions per mile (km) 551.01 (342.38) 560.04 (347.99) 9.04 (5.61) 1.6%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.68 mph (31.67 km/h)
25 mph (40.23 km/h)24.6 mph (39.58 km/h)
30 mph (48.28 km/h)29.52 mph (47.5 km/h)
35 mph (56.33 km/h)34.44 mph (55.42 km/h)
40 mph (64.37 km/h)39.35 mph (63.34 km/h)
45 mph (72.42 km/h)44.27 mph (71.25 km/h)
50 mph (80.47 km/h)49.19 mph (79.17 km/h)
55 mph (88.51 km/h)54.11 mph (87.09 km/h)
60 mph (96.56 km/h)59.03 mph (95 km/h)
65 mph (104.61 km/h)63.95 mph (102.92 km/h)
70 mph (112.65 km/h)68.87 mph (110.84 km/h)
75 mph (120.7 km/h)73.79 mph (118.75 km/h)
80 mph (128.75 km/h)78.71 mph (126.67 km/h)
85 mph (136.79 km/h)83.63 mph (134.59 km/h)
90 mph (144.84 km/h)88.55 mph (142.5 km/h)
95 mph (152.89 km/h)93.47 mph (150.42 km/h)
100 mph (160.93 km/h)98.39 mph (158.34 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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