Quote - now... Oshio suggested another way.  Find the area where the lug nut hole should be and position a flat disk.  Move points to match.  select polys inside, duplicate, extrude.

Ok, that works too, but you have to do it for each hole.  Sounds tedious.  Well, maybe.  I think the time it took me to make 5 of the disk / extrusions was way longer than making a boolean and arraying it, however, considering the cleanup time, it was about the same.

Here is an image of the boolean after I cleaned it up.  It is quads and tris, but no-ngons.

 

Glad you avoided Ngons here, because they would have made for a really nasty topology once subdivided.

Actually, for something like this, I don't even believe you need to end with any triangles either.  This could be all quads if you create the holes using the 8-junction inset technique to avoid booleans and triangles.  The 8 junction technique is simply the fact that with a minimum of 8 edges, you could easily create round holes in any surface without booleans or anything else.  Here's an example I put together really quick, similar to your geometry:

Once I smoothed it with two iterations of SubD smoothing, I ended with a very similar shape, but much cleaner topology.  All Quads.

 It could use some tweaking, obviously; but I only spent all of 15 minutes on it, to give an example.  I think it's a very viable technique for rims of any kind.  It's very fast, easy, and the results are good.  You end with a clean, quad topology that is easily edited later, and re-usable in the future.

At any rate, stay far away from booleans at all cost.  They kill the integrity of the geometry, and make it really hard to edit later on.  If you create a good base for your rims here, you may never need to model rims from scratch again; just use these as a base for all your future rim objects.  That is, if you keep the topology clean, and easy to edit.

Good luck!

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