Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
225/45r17 vs 255/30r20 Tire Comparison Side By Side
  225/45-17 255/30-20 Difference
Diameter inches (mm) 24.97 (634.3) 26.02 (661) 1.05 (26.7) 4.2%
Width inches (mm) 8.86 (225) 10.04 (255) 1.18 (30) 13.3%
Circum. inches (mm) 78.45 (1992.71) 81.76 (2076.59) 3.3 (83.88) 4.2%
Sidewall Height inches (mm) 3.99 (101.25) 3.01 (76.5) -0.97 (-24.75) -24.4%
Revolutions per mile (km) 807.61 (501.83) 774.99 (481.56) -32.62 (-20.27) -4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.84 mph (33.54 km/h)
25 mph (40.23 km/h)26.05 mph (41.93 km/h)
30 mph (48.28 km/h)31.26 mph (50.31 km/h)
35 mph (56.33 km/h)36.47 mph (58.7 km/h)
40 mph (64.37 km/h)41.68 mph (67.08 km/h)
45 mph (72.42 km/h)46.89 mph (75.47 km/h)
50 mph (80.47 km/h)52.1 mph (83.85 km/h)
55 mph (88.51 km/h)57.32 mph (92.24 km/h)
60 mph (96.56 km/h)62.53 mph (100.63 km/h)
65 mph (104.61 km/h)67.74 mph (109.01 km/h)
70 mph (112.65 km/h)72.95 mph (117.4 km/h)
75 mph (120.7 km/h)78.16 mph (125.78 km/h)
80 mph (128.75 km/h)83.37 mph (134.17 km/h)
85 mph (136.79 km/h)88.58 mph (142.55 km/h)
90 mph (144.84 km/h)93.79 mph (150.94 km/h)
95 mph (152.89 km/h)99 mph (159.32 km/h)
100 mph (160.93 km/h)104.21 mph (167.71 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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