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Convert Sizes By Country
Diameter (mm)
diameter (inches)
circumference (mm)
circumference (inches)
British/Australian
16.3
20.85
0.821
65.5
W 1/4
16.41
20.94
0.824
65.78
W 1/2
16.51
21.08
0.83
66.22
W 3/4
16.71
21.18
0.834
66.54
X
16.92
21.24
0.836
66.73
X 1/4
17.13
21.3
0.839
66.92
X 1/2
17.35
21.49
0.846
67.51
Y
17.45
21.69
0.854
68.14
Y 1/2
17.75
21.89
0.862
68.77
Z
17.97
22.1
0.87
69.43
Z +1/2
18.19
22.33
0.879
70.15
Z+1
18.35
22.6
0.89
71
Z+1.5
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