Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
305/40r23 vs 400/70r20 Tire Comparison Side By Side
  305/40-23 400/70-20 Difference
Diameter inches (mm) 32.61 (828.2) 42.05 (1068) 9.44 (239.8) 29%
Width inches (mm) 12.01 (305) 15.75 (400) 3.74 (95) 31.1%
Circum. inches (mm) 102.44 (2601.87) 132.1 (3355.22) 29.66 (753.35) 29%
Sidewall Height inches (mm) 4.8 (122) 11.02 (280) 6.22 (158) 129.5%
Revolutions per mile (km) 618.53 (384.34) 479.65 (298.04) -138.88 (-86.3) -22.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)25.79 mph (41.51 km/h)
25 mph (40.23 km/h)32.24 mph (51.88 km/h)
30 mph (48.28 km/h)38.69 mph (62.26 km/h)
35 mph (56.33 km/h)45.13 mph (72.64 km/h)
40 mph (64.37 km/h)51.58 mph (83.01 km/h)
45 mph (72.42 km/h)58.03 mph (93.39 km/h)
50 mph (80.47 km/h)64.48 mph (103.77 km/h)
55 mph (88.51 km/h)70.92 mph (114.14 km/h)
60 mph (96.56 km/h)77.37 mph (124.52 km/h)
65 mph (104.61 km/h)83.82 mph (134.9 km/h)
70 mph (112.65 km/h)90.27 mph (145.27 km/h)
75 mph (120.7 km/h)96.72 mph (155.65 km/h)
80 mph (128.75 km/h)103.16 mph (166.03 km/h)
85 mph (136.79 km/h)109.61 mph (176.4 km/h)
90 mph (144.84 km/h)116.06 mph (186.78 km/h)
95 mph (152.89 km/h)122.51 mph (197.16 km/h)
100 mph (160.93 km/h)128.95 mph (207.53 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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