Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
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175/70r15 vs 185/65r15 Tire Comparison Side By Side
  175/70-15 185/65-15 Difference
Diameter inches (mm) 24.65 (626) 24.47 (621.5) -0.18 (-4.5) -0.7%
Width inches (mm) 6.89 (175) 7.28 (185) 0.39 (10) 5.7%
Circum. inches (mm) 77.43 (1966.64) 76.87 (1952.5) -0.56 (-14.14) -0.7%
Sidewall Height inches (mm) 4.82 (122.5) 4.73 (120.25) -0.09 (-2.25) -1.8%
Revolutions per mile (km) 818.32 (508.48) 824.25 (512.16) 5.93 (3.68) 0.7%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.86 mph (31.96 km/h)
25 mph (40.23 km/h)24.82 mph (39.94 km/h)
30 mph (48.28 km/h)29.78 mph (47.93 km/h)
35 mph (56.33 km/h)34.75 mph (55.92 km/h)
40 mph (64.37 km/h)39.71 mph (63.91 km/h)
45 mph (72.42 km/h)44.68 mph (71.9 km/h)
50 mph (80.47 km/h)49.64 mph (79.89 km/h)
55 mph (88.51 km/h)54.6 mph (87.88 km/h)
60 mph (96.56 km/h)59.57 mph (95.87 km/h)
65 mph (104.61 km/h)64.53 mph (103.86 km/h)
70 mph (112.65 km/h)69.5 mph (111.84 km/h)
75 mph (120.7 km/h)74.46 mph (119.83 km/h)
80 mph (128.75 km/h)79.42 mph (127.82 km/h)
85 mph (136.79 km/h)84.39 mph (135.81 km/h)
90 mph (144.84 km/h)89.35 mph (143.8 km/h)
95 mph (152.89 km/h)94.32 mph (151.79 km/h)
100 mph (160.93 km/h)99.28 mph (159.78 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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