Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
275/45r21 vs 265/65r18 Tire Comparison Side By Side
  275/45-21 265/65-18 Difference
Diameter inches (mm) 30.74 (780.9) 31.56 (801.7) 0.82 (20.8) 2.7%
Width inches (mm) 10.83 (275) 10.43 (265) -0.39 (-10) -3.6%
Circum. inches (mm) 96.59 (2453.27) 99.16 (2518.61) 2.57 (65.35) 2.7%
Sidewall Height inches (mm) 4.87 (123.75) 6.78 (172.25) 1.91 (48.5) 39.2%
Revolutions per mile (km) 656 (407.62) 638.98 (397.04) -17.02 (-10.58) -2.6%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.53 mph (33.04 km/h)
25 mph (40.23 km/h)25.67 mph (41.31 km/h)
30 mph (48.28 km/h)30.8 mph (49.57 km/h)
35 mph (56.33 km/h)35.93 mph (57.83 km/h)
40 mph (64.37 km/h)41.07 mph (66.09 km/h)
45 mph (72.42 km/h)46.2 mph (74.35 km/h)
50 mph (80.47 km/h)51.33 mph (82.61 km/h)
55 mph (88.51 km/h)56.46 mph (90.87 km/h)
60 mph (96.56 km/h)61.6 mph (99.13 km/h)
65 mph (104.61 km/h)66.73 mph (107.39 km/h)
70 mph (112.65 km/h)71.86 mph (115.65 km/h)
75 mph (120.7 km/h)77 mph (123.92 km/h)
80 mph (128.75 km/h)82.13 mph (132.18 km/h)
85 mph (136.79 km/h)87.26 mph (140.44 km/h)
90 mph (144.84 km/h)92.4 mph (148.7 km/h)
95 mph (152.89 km/h)97.53 mph (156.96 km/h)
100 mph (160.93 km/h)102.66 mph (165.22 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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