Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
305/75r20 vs 33/12.5r20 Tire Comparison Side By Side
  305/75-20 33/12.5-20 Difference
Diameter inches (mm) 38.01 (965.5) 33.02 (838.72) -4.99 (-126.78) -13.1%
Width inches (mm) 12.01 (305) 12.52 (318) 0.51 (13) 4.3%
Circum. inches (mm) 119.42 (3033.21) 103.74 (2634.92) -15.68 (-398.29) -13.1%
Sidewall Height inches (mm) 9.01 (228.75) 6.51 (165.36) -2.5 (-63.39) -27.7%
Revolutions per mile (km) 530.57 (329.68) 610.78 (379.52) 80.2 (49.83) 15.1%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)17.37 mph (27.96 km/h)
25 mph (40.23 km/h)21.72 mph (34.95 km/h)
30 mph (48.28 km/h)26.06 mph (41.94 km/h)
35 mph (56.33 km/h)30.4 mph (48.93 km/h)
40 mph (64.37 km/h)34.75 mph (55.92 km/h)
45 mph (72.42 km/h)39.09 mph (62.91 km/h)
50 mph (80.47 km/h)43.43 mph (69.9 km/h)
55 mph (88.51 km/h)47.78 mph (76.89 km/h)
60 mph (96.56 km/h)52.12 mph (83.88 km/h)
65 mph (104.61 km/h)56.46 mph (90.87 km/h)
70 mph (112.65 km/h)60.81 mph (97.86 km/h)
75 mph (120.7 km/h)65.15 mph (104.85 km/h)
80 mph (128.75 km/h)69.5 mph (111.84 km/h)
85 mph (136.79 km/h)73.84 mph (118.83 km/h)
90 mph (144.84 km/h)78.18 mph (125.82 km/h)
95 mph (152.89 km/h)82.53 mph (132.81 km/h)
100 mph (160.93 km/h)86.87 mph (139.8 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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