Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
40/12.5r20 vs 35/12.5r17 Tire Comparison Side By Side
  40/12.5-20 35/12.5-17 Difference
Diameter inches (mm) 40.03 (1016.8) 35.03 (889.72) -5 (-127.08) -12.5%
Width inches (mm) 12.52 (318) 12.52 (318) 0 (0) 0%
Circum. inches (mm) 125.76 (3194.37) 110.04 (2795.14) -15.72 (-399.23) -12.5%
Sidewall Height inches (mm) 10.02 (254.4) 9.01 (228.96) -1 (-25.44) -10%
Revolutions per mile (km) 503.81 (313.05) 575.77 (357.76) 71.96 (44.71) 14.3%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)17.5 mph (28.16 km/h)
25 mph (40.23 km/h)21.88 mph (35.21 km/h)
30 mph (48.28 km/h)26.25 mph (42.25 km/h)
35 mph (56.33 km/h)30.63 mph (49.29 km/h)
40 mph (64.37 km/h)35 mph (56.33 km/h)
45 mph (72.42 km/h)39.38 mph (63.37 km/h)
50 mph (80.47 km/h)43.75 mph (70.41 km/h)
55 mph (88.51 km/h)48.13 mph (77.45 km/h)
60 mph (96.56 km/h)52.5 mph (84.49 km/h)
65 mph (104.61 km/h)56.88 mph (91.53 km/h)
70 mph (112.65 km/h)61.25 mph (98.57 km/h)
75 mph (120.7 km/h)65.63 mph (105.62 km/h)
80 mph (128.75 km/h)70 mph (112.66 km/h)
85 mph (136.79 km/h)74.38 mph (119.7 km/h)
90 mph (144.84 km/h)78.75 mph (126.74 km/h)
95 mph (152.89 km/h)83.13 mph (133.78 km/h)
100 mph (160.93 km/h)87.5 mph (140.82 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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