they will be machined out on a lathe, its not possible to be out of balance, this is how regular wheel spacers are made
as long they dont do it on a 3 jaw chuck....
hope they use a 4 jaw and indicate them in TRUE...
but you cant drill them on the lathe....
and if you get the bolt hole circle out of center... there is your vibration ....
just my 2 cents....
brian higdon...
