Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
225/45r21 vs 245/45r21 Tire Comparison Side By Side
  225/45-21 245/45-21 Difference
Diameter inches (mm) 28.97 (735.9) 29.68 (753.9) 0.71 (18) 2.4%
Width inches (mm) 8.86 (225) 9.65 (245) 0.79 (20) 8.9%
Circum. inches (mm) 91.02 (2311.9) 93.25 (2368.45) 2.23 (56.55) 2.4%
Sidewall Height inches (mm) 3.99 (101.25) 4.34 (110.25) 0.35 (9) 8.9%
Revolutions per mile (km) 696.11 (432.54) 679.49 (422.22) -16.62 (-10.33) -2.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.49 mph (32.97 km/h)
25 mph (40.23 km/h)25.61 mph (41.22 km/h)
30 mph (48.28 km/h)30.73 mph (49.46 km/h)
35 mph (56.33 km/h)35.86 mph (57.7 km/h)
40 mph (64.37 km/h)40.98 mph (65.95 km/h)
45 mph (72.42 km/h)46.1 mph (74.19 km/h)
50 mph (80.47 km/h)51.22 mph (82.44 km/h)
55 mph (88.51 km/h)56.35 mph (90.68 km/h)
60 mph (96.56 km/h)61.47 mph (98.92 km/h)
65 mph (104.61 km/h)66.59 mph (107.17 km/h)
70 mph (112.65 km/h)71.71 mph (115.41 km/h)
75 mph (120.7 km/h)76.83 mph (123.65 km/h)
80 mph (128.75 km/h)81.96 mph (131.9 km/h)
85 mph (136.79 km/h)87.08 mph (140.14 km/h)
90 mph (144.84 km/h)92.2 mph (148.38 km/h)
95 mph (152.89 km/h)97.32 mph (156.63 km/h)
100 mph (160.93 km/h)102.45 mph (164.87 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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