Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
38/15.5r20 vs 37/13.5r22 Tire Comparison Side By Side
  38/15.5-20 37/13.5-22 Difference
Diameter inches (mm) 37.99 (965.04) 37.12 (942.96) -0.87 (-22.08) -2.3%
Width inches (mm) 15.51 (394) 13.5 (343) -2.01 (-51) -12.9%
Circum. inches (mm) 119.36 (3031.76) 116.63 (2962.4) -2.73 (-69.37) -2.3%
Sidewall Height inches (mm) 9 (228.52) 7.56 (192.08) -1.43 (-36.44) -15.9%
Revolutions per mile (km) 530.83 (329.84) 543.26 (337.56) 12.43 (7.72) 2.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.54 mph (31.45 km/h)
25 mph (40.23 km/h)24.43 mph (39.31 km/h)
30 mph (48.28 km/h)29.31 mph (47.18 km/h)
35 mph (56.33 km/h)34.2 mph (55.04 km/h)
40 mph (64.37 km/h)39.08 mph (62.9 km/h)
45 mph (72.42 km/h)43.97 mph (70.76 km/h)
50 mph (80.47 km/h)48.86 mph (78.63 km/h)
55 mph (88.51 km/h)53.74 mph (86.49 km/h)
60 mph (96.56 km/h)58.63 mph (94.35 km/h)
65 mph (104.61 km/h)63.51 mph (102.21 km/h)
70 mph (112.65 km/h)68.4 mph (110.08 km/h)
75 mph (120.7 km/h)73.28 mph (117.94 km/h)
80 mph (128.75 km/h)78.17 mph (125.8 km/h)
85 mph (136.79 km/h)83.06 mph (133.66 km/h)
90 mph (144.84 km/h)87.94 mph (141.53 km/h)
95 mph (152.89 km/h)92.83 mph (149.39 km/h)
100 mph (160.93 km/h)97.71 mph (157.25 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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