If the bore is too small machine it bigger, too big use spacer rings: we used e70 wheels on e53 that way.

You mentioned getting them machined to start with.

A quick search revealed the hub siZe of m4.

72.4 to 74 mm (74-72.4)/2=0.8 mm needs to be removed. My brother could do that in a couple hours. (unless m4 came with multiple sizes).

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)