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 185/55r15 Tire Comparison Side By Side
  185/65-15 185/55-15 Difference
Diameter inches (mm) 24.47 (621.5) 23.01 (584.5) -1.46 (-37) -6%
Width inches (mm) 7.28 (185) 7.28 (185) 0 (0) 0%
Circum. inches (mm) 76.87 (1952.5) 72.29 (1836.26) -4.58 (-116.24) -6%
Sidewall Height inches (mm) 4.73 (120.25) 4.01 (101.75) -0.73 (-18.5) -15.4%
Revolutions per mile (km) 824.25 (512.16) 876.42 (544.58) 52.18 (32.42) 6.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)18.81 mph (30.27 km/h)
25 mph (40.23 km/h)23.51 mph (37.84 km/h)
30 mph (48.28 km/h)28.21 mph (45.41 km/h)
35 mph (56.33 km/h)32.92 mph (52.97 km/h)
40 mph (64.37 km/h)37.62 mph (60.54 km/h)
45 mph (72.42 km/h)42.32 mph (68.11 km/h)
50 mph (80.47 km/h)47.02 mph (75.68 km/h)
55 mph (88.51 km/h)51.73 mph (83.24 km/h)
60 mph (96.56 km/h)56.43 mph (90.81 km/h)
65 mph (104.61 km/h)61.13 mph (98.38 km/h)
70 mph (112.65 km/h)65.83 mph (105.95 km/h)
75 mph (120.7 km/h)70.53 mph (113.52 km/h)
80 mph (128.75 km/h)75.24 mph (121.08 km/h)
85 mph (136.79 km/h)79.94 mph (128.65 km/h)
90 mph (144.84 km/h)84.64 mph (136.22 km/h)
95 mph (152.89 km/h)89.34 mph (143.79 km/h)
100 mph (160.93 km/h)94.05 mph (151.35 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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