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 185/70r15 Tire Comparison Side By Side
  185/65-15 185/70-15 Difference
Diameter inches (mm) 24.47 (621.5) 25.2 (640) 0.73 (18.5) 3%
Width inches (mm) 7.28 (185) 7.28 (185) 0 (0) 0%
Circum. inches (mm) 76.87 (1952.5) 79.16 (2010.62) 2.29 (58.12) 3%
Sidewall Height inches (mm) 4.73 (120.25) 5.1 (129.5) 0.36 (9.25) 7.7%
Revolutions per mile (km) 824.25 (512.16) 800.42 (497.36) -23.83 (-14.8) -2.9%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.6 mph (33.15 km/h)
25 mph (40.23 km/h)25.74 mph (41.43 km/h)
30 mph (48.28 km/h)30.89 mph (49.72 km/h)
35 mph (56.33 km/h)36.04 mph (58 km/h)
40 mph (64.37 km/h)41.19 mph (66.29 km/h)
45 mph (72.42 km/h)46.34 mph (74.58 km/h)
50 mph (80.47 km/h)51.49 mph (82.86 km/h)
55 mph (88.51 km/h)56.64 mph (91.15 km/h)
60 mph (96.56 km/h)61.79 mph (99.44 km/h)
65 mph (104.61 km/h)66.93 mph (107.72 km/h)
70 mph (112.65 km/h)72.08 mph (116.01 km/h)
75 mph (120.7 km/h)77.23 mph (124.29 km/h)
80 mph (128.75 km/h)82.38 mph (132.58 km/h)
85 mph (136.79 km/h)87.53 mph (140.87 km/h)
90 mph (144.84 km/h)92.68 mph (149.15 km/h)
95 mph (152.89 km/h)97.83 mph (157.44 km/h)
100 mph (160.93 km/h)102.98 mph (165.73 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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