Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
305/25r21 vs 325/25r21 Tire Comparison Side By Side
  305/25-21 325/25-21 Difference
Diameter inches (mm) 27 (685.9) 27.4 (695.9) 0.39 (10) 1.5%
Width inches (mm) 12.01 (305) 12.8 (325) 0.79 (20) 6.6%
Circum. inches (mm) 84.84 (2154.82) 86.07 (2186.23) 1.24 (31.42) 1.5%
Sidewall Height inches (mm) 3 (76.25) 3.2 (81.25) 0.2 (5) 6.6%
Revolutions per mile (km) 746.86 (464.08) 736.13 (457.41) -10.73 (-6.67) -1.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.29 mph (32.66 km/h)
25 mph (40.23 km/h)25.36 mph (40.82 km/h)
30 mph (48.28 km/h)30.44 mph (48.98 km/h)
35 mph (56.33 km/h)35.51 mph (57.15 km/h)
40 mph (64.37 km/h)40.58 mph (65.31 km/h)
45 mph (72.42 km/h)45.66 mph (73.48 km/h)
50 mph (80.47 km/h)50.73 mph (81.64 km/h)
55 mph (88.51 km/h)55.8 mph (89.8 km/h)
60 mph (96.56 km/h)60.87 mph (97.97 km/h)
65 mph (104.61 km/h)65.95 mph (106.13 km/h)
70 mph (112.65 km/h)71.02 mph (114.3 km/h)
75 mph (120.7 km/h)76.09 mph (122.46 km/h)
80 mph (128.75 km/h)81.17 mph (130.62 km/h)
85 mph (136.79 km/h)86.24 mph (138.79 km/h)
90 mph (144.84 km/h)91.31 mph (146.95 km/h)
95 mph (152.89 km/h)96.39 mph (155.12 km/h)
100 mph (160.93 km/h)101.46 mph (163.28 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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