Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
345/25r20 vs 345/20r21 Tire Comparison Side By Side
  345/25-20 345/20-21 Difference
Diameter inches (mm) 26.79 (680.5) 26.43 (671.4) -0.36 (-9.1) -1.3%
Width inches (mm) 13.58 (345) 13.58 (345) 0 (0) 0%
Circum. inches (mm) 84.17 (2137.85) 83.04 (2109.27) -1.13 (-28.59) -1.3%
Sidewall Height inches (mm) 3.4 (86.25) 2.72 (69) -0.68 (-17.25) -20%
Revolutions per mile (km) 752.78 (467.76) 762.99 (474.1) 10.2 (6.34) 1.4%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)19.73 mph (31.76 km/h)
25 mph (40.23 km/h)24.67 mph (39.7 km/h)
30 mph (48.28 km/h)29.6 mph (47.63 km/h)
35 mph (56.33 km/h)34.53 mph (55.57 km/h)
40 mph (64.37 km/h)39.47 mph (63.51 km/h)
45 mph (72.42 km/h)44.4 mph (71.45 km/h)
50 mph (80.47 km/h)49.33 mph (79.39 km/h)
55 mph (88.51 km/h)54.26 mph (87.33 km/h)
60 mph (96.56 km/h)59.2 mph (95.27 km/h)
65 mph (104.61 km/h)64.13 mph (103.21 km/h)
70 mph (112.65 km/h)69.06 mph (111.15 km/h)
75 mph (120.7 km/h)74 mph (119.09 km/h)
80 mph (128.75 km/h)78.93 mph (127.03 km/h)
85 mph (136.79 km/h)83.86 mph (134.97 km/h)
90 mph (144.84 km/h)88.8 mph (142.9 km/h)
95 mph (152.89 km/h)93.73 mph (150.84 km/h)
100 mph (160.93 km/h)98.66 mph (158.78 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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