Got you covered, here is the thread to read :
http://newbeetle.org/forums/styling-modifications/51364-moon-hubcaps-stock-16-wheel.html
One thing I would recommend as a personal side note of my restoration of some early Beetle wheels. I use some stumpy 3/16 pop rivets with a thin backing washer. I pop them from behind the rim with the washer under the ''pulled'' part of the pop holding the clip. Its much easier than trying to make the original solid rivets work
http://newbeetle.org/forums/styling-modifications/51364-moon-hubcaps-stock-16-wheel.html
One thing I would recommend as a personal side note of my restoration of some early Beetle wheels. I use some stumpy 3/16 pop rivets with a thin backing washer. I pop them from behind the rim with the washer under the ''pulled'' part of the pop holding the clip. Its much easier than trying to make the original solid rivets work