Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
185/65r15 vs 175/80r15 Tire Comparison Side By Side
  185/65-15 175/80-15 Difference
Diameter inches (mm) 24.47 (621.5) 26.02 (661) 1.56 (39.5) 6.4%
Width inches (mm) 7.28 (185) 6.89 (175) -0.39 (-10) -5.4%
Circum. inches (mm) 76.87 (1952.5) 81.76 (2076.59) 4.89 (124.09) 6.4%
Sidewall Height inches (mm) 4.73 (120.25) 5.51 (140) 0.78 (19.75) 16.4%
Revolutions per mile (km) 824.25 (512.16) 774.99 (481.56) -49.26 (-30.61) -6%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)21.27 mph (34.23 km/h)
25 mph (40.23 km/h)26.59 mph (42.79 km/h)
30 mph (48.28 km/h)31.91 mph (51.35 km/h)
35 mph (56.33 km/h)37.22 mph (59.91 km/h)
40 mph (64.37 km/h)42.54 mph (68.47 km/h)
45 mph (72.42 km/h)47.86 mph (77.02 km/h)
50 mph (80.47 km/h)53.18 mph (85.58 km/h)
55 mph (88.51 km/h)58.5 mph (94.14 km/h)
60 mph (96.56 km/h)63.81 mph (102.7 km/h)
65 mph (104.61 km/h)69.13 mph (111.26 km/h)
70 mph (112.65 km/h)74.45 mph (119.81 km/h)
75 mph (120.7 km/h)79.77 mph (128.37 km/h)
80 mph (128.75 km/h)85.08 mph (136.93 km/h)
85 mph (136.79 km/h)90.4 mph (145.49 km/h)
90 mph (144.84 km/h)95.72 mph (154.05 km/h)
95 mph (152.89 km/h)101.04 mph (162.6 km/h)
100 mph (160.93 km/h)106.36 mph (171.16 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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