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 395/85r22.5 Tire Comparison Side By Side
  40/12.5-20 395/85-22.5 Difference
Diameter inches (mm) 40.03 (1016.8) 48.94 (1243) 8.91 (226.2) 22.2%
Width inches (mm) 12.52 (318) 15.55 (395) 3.03 (77) 24.2%
Circum. inches (mm) 125.76 (3194.37) 153.74 (3905) 27.98 (710.63) 22.2%
Sidewall Height inches (mm) 10.02 (254.4) 13.22 (335.75) 3.2 (81.35) 32%
Revolutions per mile (km) 503.81 (313.05) 412.12 (256.08) -91.68 (-56.97) -18.2%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)24.45 mph (39.35 km/h)
25 mph (40.23 km/h)30.56 mph (49.18 km/h)
30 mph (48.28 km/h)36.67 mph (59.02 km/h)
35 mph (56.33 km/h)42.79 mph (68.86 km/h)
40 mph (64.37 km/h)48.9 mph (78.69 km/h)
45 mph (72.42 km/h)55.01 mph (88.53 km/h)
50 mph (80.47 km/h)61.12 mph (98.37 km/h)
55 mph (88.51 km/h)67.24 mph (108.21 km/h)
60 mph (96.56 km/h)73.35 mph (118.04 km/h)
65 mph (104.61 km/h)79.46 mph (127.88 km/h)
70 mph (112.65 km/h)85.57 mph (137.72 km/h)
75 mph (120.7 km/h)91.68 mph (147.55 km/h)
80 mph (128.75 km/h)97.8 mph (157.39 km/h)
85 mph (136.79 km/h)103.91 mph (167.23 km/h)
90 mph (144.84 km/h)110.02 mph (177.06 km/h)
95 mph (152.89 km/h)116.13 mph (186.9 km/h)
100 mph (160.93 km/h)122.25 mph (196.74 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
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
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