Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
275/40r21 vs 255/40r21 Tire Comparison Side By Side
  275/40-21 255/40-21 Difference
Diameter inches (mm) 29.66 (753.4) 29.03 (737.4) -0.63 (-16) -2.1%
Width inches (mm) 10.83 (275) 10.04 (255) -0.79 (-20) -7.3%
Circum. inches (mm) 93.18 (2366.88) 91.21 (2316.61) -1.98 (-50.27) -2.1%
Sidewall Height inches (mm) 4.33 (110) 4.02 (102) -0.31 (-8) -7.3%
Revolutions per mile (km) 679.94 (422.5) 694.7 (431.66) 14.75 (9.17) 2.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.58 mph (31.5 km/h)
25 mph (40.23 km/h)24.47 mph (39.38 km/h)
30 mph (48.28 km/h)29.36 mph (47.26 km/h)
35 mph (56.33 km/h)34.26 mph (55.13 km/h)
40 mph (64.37 km/h)39.15 mph (63.01 km/h)
45 mph (72.42 km/h)44.04 mph (70.88 km/h)
50 mph (80.47 km/h)48.94 mph (78.76 km/h)
55 mph (88.51 km/h)53.83 mph (86.63 km/h)
60 mph (96.56 km/h)58.73 mph (94.51 km/h)
65 mph (104.61 km/h)63.62 mph (102.39 km/h)
70 mph (112.65 km/h)68.51 mph (110.26 km/h)
75 mph (120.7 km/h)73.41 mph (118.14 km/h)
80 mph (128.75 km/h)78.3 mph (126.01 km/h)
85 mph (136.79 km/h)83.19 mph (133.89 km/h)
90 mph (144.84 km/h)88.09 mph (141.77 km/h)
95 mph (152.89 km/h)92.98 mph (149.64 km/h)
100 mph (160.93 km/h)97.88 mph (157.52 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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