Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
225/30r20 vs 245/30r20 Tire Comparison Side By Side
  225/30-20 245/30-20 Difference
Diameter inches (mm) 25.31 (643) 25.79 (655) 0.47 (12) 1.9%
Width inches (mm) 8.86 (225) 9.65 (245) 0.79 (20) 8.9%
Circum. inches (mm) 79.53 (2020.04) 81.01 (2057.74) 1.48 (37.7) 1.9%
Sidewall Height inches (mm) 2.66 (67.5) 2.89 (73.5) 0.24 (6) 8.9%
Revolutions per mile (km) 796.69 (495.04) 782.09 (485.97) -14.6 (-9.07) -1.8%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.37 mph (32.79 km/h)
25 mph (40.23 km/h)25.47 mph (40.98 km/h)
30 mph (48.28 km/h)30.56 mph (49.18 km/h)
35 mph (56.33 km/h)35.65 mph (57.38 km/h)
40 mph (64.37 km/h)40.75 mph (65.58 km/h)
45 mph (72.42 km/h)45.84 mph (73.77 km/h)
50 mph (80.47 km/h)50.93 mph (81.97 km/h)
55 mph (88.51 km/h)56.03 mph (90.17 km/h)
60 mph (96.56 km/h)61.12 mph (98.36 km/h)
65 mph (104.61 km/h)66.21 mph (106.56 km/h)
70 mph (112.65 km/h)71.31 mph (114.76 km/h)
75 mph (120.7 km/h)76.4 mph (122.95 km/h)
80 mph (128.75 km/h)81.49 mph (131.15 km/h)
85 mph (136.79 km/h)86.59 mph (139.35 km/h)
90 mph (144.84 km/h)91.68 mph (147.54 km/h)
95 mph (152.89 km/h)96.77 mph (155.74 km/h)
100 mph (160.93 km/h)101.87 mph (163.94 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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