Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
175/45r15 vs 185/45r15 Tire Comparison Side By Side
  175/45-15 185/45-15 Difference
Diameter inches (mm) 21.2 (538.5) 21.56 (547.5) 0.35 (9) 1.7%
Width inches (mm) 6.89 (175) 7.28 (185) 0.39 (10) 5.7%
Circum. inches (mm) 66.6 (1691.75) 67.72 (1720.02) 1.11 (28.27) 1.7%
Sidewall Height inches (mm) 3.1 (78.75) 3.28 (83.25) 0.18 (4.5) 5.7%
Revolutions per mile (km) 951.29 (591.1) 935.65 (581.39) -15.64 (-9.72) -1.6%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.33 mph (32.72 km/h)
25 mph (40.23 km/h)25.42 mph (40.91 km/h)
30 mph (48.28 km/h)30.5 mph (49.09 km/h)
35 mph (56.33 km/h)35.58 mph (57.27 km/h)
40 mph (64.37 km/h)40.67 mph (65.45 km/h)
45 mph (72.42 km/h)45.75 mph (73.63 km/h)
50 mph (80.47 km/h)50.84 mph (81.81 km/h)
55 mph (88.51 km/h)55.92 mph (89.99 km/h)
60 mph (96.56 km/h)61 mph (98.17 km/h)
65 mph (104.61 km/h)66.09 mph (106.36 km/h)
70 mph (112.65 km/h)71.17 mph (114.54 km/h)
75 mph (120.7 km/h)76.25 mph (122.72 km/h)
80 mph (128.75 km/h)81.34 mph (130.9 km/h)
85 mph (136.79 km/h)86.42 mph (139.08 km/h)
90 mph (144.84 km/h)91.5 mph (147.26 km/h)
95 mph (152.89 km/h)96.59 mph (155.44 km/h)
100 mph (160.93 km/h)101.67 mph (163.62 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
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
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