Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
315/55r20 vs 325/55r20 Tire Comparison Side By Side
  315/55-20 325/55-20 Difference
Diameter inches (mm) 33.64 (854.5) 34.07 (865.5) 0.43 (11) 1.3%
Width inches (mm) 12.4 (315) 12.8 (325) 0.39 (10) 3.2%
Circum. inches (mm) 105.69 (2684.49) 107.05 (2719.05) 1.36 (34.56) 1.3%
Sidewall Height inches (mm) 6.82 (173.25) 7.04 (178.75) 0.22 (5.5) 3.2%
Revolutions per mile (km) 599.5 (372.51) 591.88 (367.78) -7.62 (-4.73) -1.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.26 mph (32.6 km/h)
25 mph (40.23 km/h)25.32 mph (40.75 km/h)
30 mph (48.28 km/h)30.39 mph (48.9 km/h)
35 mph (56.33 km/h)35.45 mph (57.05 km/h)
40 mph (64.37 km/h)40.51 mph (65.2 km/h)
45 mph (72.42 km/h)45.58 mph (73.35 km/h)
50 mph (80.47 km/h)50.64 mph (81.5 km/h)
55 mph (88.51 km/h)55.71 mph (89.65 km/h)
60 mph (96.56 km/h)60.77 mph (97.8 km/h)
65 mph (104.61 km/h)65.84 mph (105.95 km/h)
70 mph (112.65 km/h)70.9 mph (114.1 km/h)
75 mph (120.7 km/h)75.97 mph (122.25 km/h)
80 mph (128.75 km/h)81.03 mph (130.41 km/h)
85 mph (136.79 km/h)86.09 mph (138.56 km/h)
90 mph (144.84 km/h)91.16 mph (146.71 km/h)
95 mph (152.89 km/h)96.22 mph (154.86 km/h)
100 mph (160.93 km/h)101.29 mph (163.01 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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