Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
345/30r20 vs 365/45r20 Tire Comparison Side By Side
  345/30-20 365/45-20 Difference
Diameter inches (mm) 28.15 (715) 32.93 (836.5) 4.78 (121.5) 17%
Width inches (mm) 13.58 (345) 14.37 (365) 0.79 (20) 5.8%
Circum. inches (mm) 88.43 (2246.24) 103.46 (2627.94) 15.03 (381.7) 17%
Sidewall Height inches (mm) 4.07 (103.5) 6.47 (164.25) 2.39 (60.75) 58.7%
Revolutions per mile (km) 716.46 (445.19) 612.4 (380.53) -104.06 (-64.66) -14.5%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)23.4 mph (37.66 km/h)
25 mph (40.23 km/h)29.25 mph (47.07 km/h)
30 mph (48.28 km/h)35.1 mph (56.48 km/h)
35 mph (56.33 km/h)40.95 mph (65.9 km/h)
40 mph (64.37 km/h)46.8 mph (75.31 km/h)
45 mph (72.42 km/h)52.65 mph (84.73 km/h)
50 mph (80.47 km/h)58.5 mph (94.14 km/h)
55 mph (88.51 km/h)64.35 mph (103.56 km/h)
60 mph (96.56 km/h)70.2 mph (112.97 km/h)
65 mph (104.61 km/h)76.05 mph (122.38 km/h)
70 mph (112.65 km/h)81.9 mph (131.8 km/h)
75 mph (120.7 km/h)87.74 mph (141.21 km/h)
80 mph (128.75 km/h)93.59 mph (150.63 km/h)
85 mph (136.79 km/h)99.44 mph (160.04 km/h)
90 mph (144.84 km/h)105.29 mph (169.45 km/h)
95 mph (152.89 km/h)111.14 mph (178.87 km/h)
100 mph (160.93 km/h)116.99 mph (188.28 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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