Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
255/40r20 vs 245/45r20 Tire Comparison Side By Side
  255/40-20 245/45-20 Difference
Diameter inches (mm) 28.03 (712) 28.68 (728.5) 0.65 (16.5) 2.3%
Width inches (mm) 10.04 (255) 9.65 (245) -0.39 (-10) -3.9%
Circum. inches (mm) 88.06 (2236.81) 90.1 (2288.65) 2.04 (51.84) 2.3%
Sidewall Height inches (mm) 4.02 (102) 4.34 (110.25) 0.32 (8.25) 8.1%
Revolutions per mile (km) 719.48 (447.06) 703.18 (436.94) -16.3 (-10.13) -2.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.46 mph (32.93 km/h)
25 mph (40.23 km/h)25.58 mph (41.17 km/h)
30 mph (48.28 km/h)30.7 mph (49.4 km/h)
35 mph (56.33 km/h)35.81 mph (57.63 km/h)
40 mph (64.37 km/h)40.93 mph (65.87 km/h)
45 mph (72.42 km/h)46.04 mph (74.1 km/h)
50 mph (80.47 km/h)51.16 mph (82.33 km/h)
55 mph (88.51 km/h)56.27 mph (90.57 km/h)
60 mph (96.56 km/h)61.39 mph (98.8 km/h)
65 mph (104.61 km/h)66.51 mph (107.03 km/h)
70 mph (112.65 km/h)71.62 mph (115.26 km/h)
75 mph (120.7 km/h)76.74 mph (123.5 km/h)
80 mph (128.75 km/h)81.85 mph (131.73 km/h)
85 mph (136.79 km/h)86.97 mph (139.96 km/h)
90 mph (144.84 km/h)92.09 mph (148.2 km/h)
95 mph (152.89 km/h)97.2 mph (156.43 km/h)
100 mph (160.93 km/h)102.32 mph (164.66 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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