Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
170/80r15 vs 180/80r15 Tire Comparison Side By Side
  170/80-15 180/80-15 Difference
Diameter inches (mm) 25.71 (653) 26.34 (669) 0.63 (16) 2.5%
Width inches (mm) 6.69 (170) 7.09 (180) 0.39 (10) 5.9%
Circum. inches (mm) 80.77 (2051.46) 82.75 (2101.73) 1.98 (50.27) 2.5%
Sidewall Height inches (mm) 5.35 (136) 5.67 (144) 0.31 (8) 5.9%
Revolutions per mile (km) 784.49 (487.46) 765.73 (475.8) -18.76 (-11.66) -2.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.49 mph (32.98 km/h)
25 mph (40.23 km/h)25.61 mph (41.22 km/h)
30 mph (48.28 km/h)30.74 mph (49.46 km/h)
35 mph (56.33 km/h)35.86 mph (57.71 km/h)
40 mph (64.37 km/h)40.98 mph (65.95 km/h)
45 mph (72.42 km/h)46.1 mph (74.2 km/h)
50 mph (80.47 km/h)51.23 mph (82.44 km/h)
55 mph (88.51 km/h)56.35 mph (90.68 km/h)
60 mph (96.56 km/h)61.47 mph (98.93 km/h)
65 mph (104.61 km/h)66.59 mph (107.17 km/h)
70 mph (112.65 km/h)71.72 mph (115.41 km/h)
75 mph (120.7 km/h)76.84 mph (123.66 km/h)
80 mph (128.75 km/h)81.96 mph (131.9 km/h)
85 mph (136.79 km/h)87.08 mph (140.15 km/h)
90 mph (144.84 km/h)92.21 mph (148.39 km/h)
95 mph (152.89 km/h)97.33 mph (156.63 km/h)
100 mph (160.93 km/h)102.45 mph (164.88 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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