Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
305/60r18 vs 285/65r18 Tire Comparison Side By Side
  305/60-18 285/65-18 Difference
Diameter inches (mm) 32.41 (823.2) 32.59 (827.7) 0.18 (4.5) 0.5%
Width inches (mm) 12.01 (305) 11.22 (285) -0.79 (-20) -6.6%
Circum. inches (mm) 101.82 (2586.16) 102.37 (2600.3) 0.56 (14.14) 0.5%
Sidewall Height inches (mm) 7.2 (183) 7.29 (185.25) 0.09 (2.25) 1.2%
Revolutions per mile (km) 622.29 (386.67) 618.91 (384.57) -3.38 (-2.1) -0.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.11 mph (32.36 km/h)
25 mph (40.23 km/h)25.14 mph (40.45 km/h)
30 mph (48.28 km/h)30.16 mph (48.54 km/h)
35 mph (56.33 km/h)35.19 mph (56.64 km/h)
40 mph (64.37 km/h)40.22 mph (64.73 km/h)
45 mph (72.42 km/h)45.25 mph (72.82 km/h)
50 mph (80.47 km/h)50.27 mph (80.91 km/h)
55 mph (88.51 km/h)55.3 mph (89 km/h)
60 mph (96.56 km/h)60.33 mph (97.09 km/h)
65 mph (104.61 km/h)65.36 mph (105.18 km/h)
70 mph (112.65 km/h)70.38 mph (113.27 km/h)
75 mph (120.7 km/h)75.41 mph (121.36 km/h)
80 mph (128.75 km/h)80.44 mph (129.45 km/h)
85 mph (136.79 km/h)85.46 mph (137.54 km/h)
90 mph (144.84 km/h)90.49 mph (145.63 km/h)
95 mph (152.89 km/h)95.52 mph (153.72 km/h)
100 mph (160.93 km/h)100.55 mph (161.81 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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