Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
165/75r15 vs 185/65r15 Tire Comparison Side By Side
  165/75-15 185/65-15 Difference
Diameter inches (mm) 24.74 (628.5) 24.47 (621.5) -0.28 (-7) -1.1%
Width inches (mm) 6.5 (165) 7.28 (185) 0.79 (20) 12.1%
Circum. inches (mm) 77.74 (1974.49) 76.87 (1952.5) -0.87 (-21.99) -1.1%
Sidewall Height inches (mm) 4.87 (123.75) 4.73 (120.25) -0.14 (-3.5) -2.8%
Revolutions per mile (km) 815.07 (506.46) 824.25 (512.16) 9.18 (5.7) 1.1%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.78 mph (31.83 km/h)
25 mph (40.23 km/h)24.72 mph (39.79 km/h)
30 mph (48.28 km/h)29.67 mph (47.74 km/h)
35 mph (56.33 km/h)34.61 mph (55.7 km/h)
40 mph (64.37 km/h)39.55 mph (63.66 km/h)
45 mph (72.42 km/h)44.5 mph (71.61 km/h)
50 mph (80.47 km/h)49.44 mph (79.57 km/h)
55 mph (88.51 km/h)54.39 mph (87.53 km/h)
60 mph (96.56 km/h)59.33 mph (95.49 km/h)
65 mph (104.61 km/h)64.28 mph (103.44 km/h)
70 mph (112.65 km/h)69.22 mph (111.4 km/h)
75 mph (120.7 km/h)74.16 mph (119.36 km/h)
80 mph (128.75 km/h)79.11 mph (127.31 km/h)
85 mph (136.79 km/h)84.05 mph (135.27 km/h)
90 mph (144.84 km/h)89 mph (143.23 km/h)
95 mph (152.89 km/h)93.94 mph (151.19 km/h)
100 mph (160.93 km/h)98.89 mph (159.14 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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