Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
255/50r21 vs 235/55r20 Tire Comparison Side By Side
  255/50-21 235/55-20 Difference
Diameter inches (mm) 31.04 (788.4) 30.18 (766.5) -0.86 (-21.9) -2.8%
Width inches (mm) 10.04 (255) 9.25 (235) -0.79 (-20) -7.8%
Circum. inches (mm) 97.51 (2476.83) 94.8 (2408.03) -2.71 (-68.8) -2.8%
Sidewall Height inches (mm) 5.02 (127.5) 5.09 (129.25) 0.07 (1.75) 1.4%
Revolutions per mile (km) 649.76 (403.74) 668.32 (415.28) 18.56 (11.54) 2.9%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.44 mph (31.29 km/h)
25 mph (40.23 km/h)24.31 mph (39.12 km/h)
30 mph (48.28 km/h)29.17 mph (46.94 km/h)
35 mph (56.33 km/h)34.03 mph (54.76 km/h)
40 mph (64.37 km/h)38.89 mph (62.59 km/h)
45 mph (72.42 km/h)43.75 mph (70.41 km/h)
50 mph (80.47 km/h)48.61 mph (78.23 km/h)
55 mph (88.51 km/h)53.47 mph (86.06 km/h)
60 mph (96.56 km/h)58.33 mph (93.88 km/h)
65 mph (104.61 km/h)63.19 mph (101.7 km/h)
70 mph (112.65 km/h)68.06 mph (109.53 km/h)
75 mph (120.7 km/h)72.92 mph (117.35 km/h)
80 mph (128.75 km/h)77.78 mph (125.17 km/h)
85 mph (136.79 km/h)82.64 mph (132.99 km/h)
90 mph (144.84 km/h)87.5 mph (140.82 km/h)
95 mph (152.89 km/h)92.36 mph (148.64 km/h)
100 mph (160.93 km/h)97.22 mph (156.46 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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