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 266/50r20 Tire Comparison Side By Side
  255/50-21 266/50-20 Difference
Diameter inches (mm) 31.04 (788.4) 30.47 (774) -0.57 (-14.4) -1.8%
Width inches (mm) 10.04 (255) 10.47 (266) 0.43 (11) 4.3%
Circum. inches (mm) 97.51 (2476.83) 95.73 (2431.59) -1.78 (-45.24) -1.8%
Sidewall Height inches (mm) 5.02 (127.5) 5.24 (133) 0.22 (5.5) 4.3%
Revolutions per mile (km) 649.76 (403.74) 661.85 (411.25) 12.09 (7.51) 1.9%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.63 mph (31.6 km/h)
25 mph (40.23 km/h)24.54 mph (39.5 km/h)
30 mph (48.28 km/h)29.45 mph (47.4 km/h)
35 mph (56.33 km/h)34.36 mph (55.3 km/h)
40 mph (64.37 km/h)39.27 mph (63.2 km/h)
45 mph (72.42 km/h)44.18 mph (71.1 km/h)
50 mph (80.47 km/h)49.09 mph (79 km/h)
55 mph (88.51 km/h)54 mph (86.9 km/h)
60 mph (96.56 km/h)58.9 mph (94.8 km/h)
65 mph (104.61 km/h)63.81 mph (102.7 km/h)
70 mph (112.65 km/h)68.72 mph (110.6 km/h)
75 mph (120.7 km/h)73.63 mph (118.5 km/h)
80 mph (128.75 km/h)78.54 mph (126.4 km/h)
85 mph (136.79 km/h)83.45 mph (134.3 km/h)
90 mph (144.84 km/h)88.36 mph (142.2 km/h)
95 mph (152.89 km/h)93.26 mph (150.1 km/h)
100 mph (160.93 km/h)98.17 mph (158 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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