Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
325/30r21 vs 315/35r20 Tire Comparison Side By Side
  325/30-21 315/35-20 Difference
Diameter inches (mm) 28.68 (728.4) 28.68 (728.5) 0 (0.1) 0%
Width inches (mm) 12.8 (325) 12.4 (315) -0.39 (-10) -3.1%
Circum. inches (mm) 90.09 (2288.34) 90.1 (2288.65) 0.01 (0.31) 0%
Sidewall Height inches (mm) 3.84 (97.5) 4.34 (110.25) 0.5 (12.75) 13.1%
Revolutions per mile (km) 703.28 (437) 703.18 (436.94) -0.1 (-0.06) -0%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20 mph (32.19 km/h)
25 mph (40.23 km/h)25 mph (40.24 km/h)
30 mph (48.28 km/h)30 mph (48.29 km/h)
35 mph (56.33 km/h)35 mph (56.33 km/h)
40 mph (64.37 km/h)40.01 mph (64.38 km/h)
45 mph (72.42 km/h)45.01 mph (72.43 km/h)
50 mph (80.47 km/h)50.01 mph (80.48 km/h)
55 mph (88.51 km/h)55.01 mph (88.53 km/h)
60 mph (96.56 km/h)60.01 mph (96.57 km/h)
65 mph (104.61 km/h)65.01 mph (104.62 km/h)
70 mph (112.65 km/h)70.01 mph (112.67 km/h)
75 mph (120.7 km/h)75.01 mph (120.72 km/h)
80 mph (128.75 km/h)80.01 mph (128.77 km/h)
85 mph (136.79 km/h)85.01 mph (136.81 km/h)
90 mph (144.84 km/h)90.01 mph (144.86 km/h)
95 mph (152.89 km/h)95.01 mph (152.91 km/h)
100 mph (160.93 km/h)100.01 mph (160.96 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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