Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
235/45r21 vs 265/45r21 Tire Comparison Side By Side
  235/45-21 265/45-21 Difference
Diameter inches (mm) 29.33 (744.9) 30.39 (771.9) 1.06 (27) 3.6%
Width inches (mm) 9.25 (235) 10.43 (265) 1.18 (30) 12.8%
Circum. inches (mm) 92.13 (2340.17) 95.47 (2425) 3.34 (84.82) 3.6%
Sidewall Height inches (mm) 4.16 (105.75) 4.69 (119.25) 0.53 (13.5) 12.8%
Revolutions per mile (km) 687.7 (427.32) 663.65 (412.37) -24.05 (-14.95) -3.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.72 mph (33.35 km/h)
25 mph (40.23 km/h)25.91 mph (41.69 km/h)
30 mph (48.28 km/h)31.09 mph (50.03 km/h)
35 mph (56.33 km/h)36.27 mph (58.37 km/h)
40 mph (64.37 km/h)41.45 mph (66.71 km/h)
45 mph (72.42 km/h)46.63 mph (75.05 km/h)
50 mph (80.47 km/h)51.81 mph (83.38 km/h)
55 mph (88.51 km/h)56.99 mph (91.72 km/h)
60 mph (96.56 km/h)62.17 mph (100.06 km/h)
65 mph (104.61 km/h)67.36 mph (108.4 km/h)
70 mph (112.65 km/h)72.54 mph (116.74 km/h)
75 mph (120.7 km/h)77.72 mph (125.08 km/h)
80 mph (128.75 km/h)82.9 mph (133.41 km/h)
85 mph (136.79 km/h)88.08 mph (141.75 km/h)
90 mph (144.84 km/h)93.26 mph (150.09 km/h)
95 mph (152.89 km/h)98.44 mph (158.43 km/h)
100 mph (160.93 km/h)103.62 mph (166.77 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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