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 305/30r20 Tire Comparison Side By Side
  325/25-20 305/30-20 Difference
Diameter inches (mm) 26.4 (670.5) 27.2 (691) 0.81 (20.5) 3.1%
Width inches (mm) 12.8 (325) 12.01 (305) -0.79 (-20) -6.2%
Circum. inches (mm) 82.93 (2106.44) 85.47 (2170.84) 2.54 (64.4) 3.1%
Sidewall Height inches (mm) 3.2 (81.25) 3.6 (91.5) 0.4 (10.25) 12.6%
Revolutions per mile (km) 764.01 (474.73) 741.35 (460.65) -22.67 (-14.08) -3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.61 mph (33.17 km/h)
25 mph (40.23 km/h)25.76 mph (41.46 km/h)
30 mph (48.28 km/h)30.92 mph (49.76 km/h)
35 mph (56.33 km/h)36.07 mph (58.05 km/h)
40 mph (64.37 km/h)41.22 mph (66.34 km/h)
45 mph (72.42 km/h)46.38 mph (74.63 km/h)
50 mph (80.47 km/h)51.53 mph (82.93 km/h)
55 mph (88.51 km/h)56.68 mph (91.22 km/h)
60 mph (96.56 km/h)61.83 mph (99.51 km/h)
65 mph (104.61 km/h)66.99 mph (107.81 km/h)
70 mph (112.65 km/h)72.14 mph (116.1 km/h)
75 mph (120.7 km/h)77.29 mph (124.39 km/h)
80 mph (128.75 km/h)82.45 mph (132.68 km/h)
85 mph (136.79 km/h)87.6 mph (140.98 km/h)
90 mph (144.84 km/h)92.75 mph (149.27 km/h)
95 mph (152.89 km/h)97.9 mph (157.56 km/h)
100 mph (160.93 km/h)103.06 mph (165.86 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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