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 305/70r18 Tire Comparison Side By Side
  305/60-18 305/70-18 Difference
Diameter inches (mm) 32.41 (823.2) 34.81 (884.2) 2.4 (61) 7.4%
Width inches (mm) 12.01 (305) 12.01 (305) 0 (0) 0%
Circum. inches (mm) 101.82 (2586.16) 109.36 (2777.8) 7.54 (191.64) 7.4%
Sidewall Height inches (mm) 7.2 (183) 8.41 (213.5) 1.2 (30.5) 16.7%
Revolutions per mile (km) 622.29 (386.67) 579.36 (360) -42.93 (-26.68) -6.9%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)21.48 mph (34.57 km/h)
25 mph (40.23 km/h)26.85 mph (43.22 km/h)
30 mph (48.28 km/h)32.22 mph (51.86 km/h)
35 mph (56.33 km/h)37.59 mph (60.5 km/h)
40 mph (64.37 km/h)42.96 mph (69.14 km/h)
45 mph (72.42 km/h)48.33 mph (77.79 km/h)
50 mph (80.47 km/h)53.71 mph (86.43 km/h)
55 mph (88.51 km/h)59.08 mph (95.07 km/h)
60 mph (96.56 km/h)64.45 mph (103.72 km/h)
65 mph (104.61 km/h)69.82 mph (112.36 km/h)
70 mph (112.65 km/h)75.19 mph (121 km/h)
75 mph (120.7 km/h)80.56 mph (129.65 km/h)
80 mph (128.75 km/h)85.93 mph (138.29 km/h)
85 mph (136.79 km/h)91.3 mph (146.93 km/h)
90 mph (144.84 km/h)96.67 mph (155.57 km/h)
95 mph (152.89 km/h)102.04 mph (164.22 km/h)
100 mph (160.93 km/h)107.41 mph (172.86 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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