Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
325/25r20 vs 315/35r20 Tire Comparison Side By Side
  325/25-20 315/35-20 Difference
Diameter inches (mm) 26.4 (670.5) 28.68 (728.5) 2.28 (58) 8.7%
Width inches (mm) 12.8 (325) 12.4 (315) -0.39 (-10) -3.1%
Circum. inches (mm) 82.93 (2106.44) 90.1 (2288.65) 7.17 (182.21) 8.7%
Sidewall Height inches (mm) 3.2 (81.25) 4.34 (110.25) 1.14 (29) 35.7%
Revolutions per mile (km) 764.01 (474.73) 703.18 (436.94) -60.83 (-37.8) -8%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)21.73 mph (34.97 km/h)
25 mph (40.23 km/h)27.16 mph (43.71 km/h)
30 mph (48.28 km/h)32.6 mph (52.46 km/h)
35 mph (56.33 km/h)38.03 mph (61.2 km/h)
40 mph (64.37 km/h)43.46 mph (69.94 km/h)
45 mph (72.42 km/h)48.89 mph (78.69 km/h)
50 mph (80.47 km/h)54.33 mph (87.43 km/h)
55 mph (88.51 km/h)59.76 mph (96.17 km/h)
60 mph (96.56 km/h)65.19 mph (104.91 km/h)
65 mph (104.61 km/h)70.62 mph (113.66 km/h)
70 mph (112.65 km/h)76.06 mph (122.4 km/h)
75 mph (120.7 km/h)81.49 mph (131.14 km/h)
80 mph (128.75 km/h)86.92 mph (139.88 km/h)
85 mph (136.79 km/h)92.35 mph (148.63 km/h)
90 mph (144.84 km/h)97.79 mph (157.37 km/h)
95 mph (152.89 km/h)103.22 mph (166.11 km/h)
100 mph (160.93 km/h)108.65 mph (174.86 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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