[orange4boy]

First one done. I changed my mounting system slightly from my first idea to save weight and complexity. These are mounted with 1/4-20 NC cap head socket screws. I will relpace with stainless once I pick some up.

I carefully laid out the discs and drilled 4 3/16 pilot holes. I then used the disc as a template to mark the aluminum rim. I measured the offset and calculated the depth of hole required to drill and tap. Drilled the pilot holes with a special drill attachment to stay square. Used the same attachment to tap first with a spiral tap, then with a bottoming tap. Then I drilled the pilot holes on the discs to 1/4", popped in the screws and backed them up, slightly loose, with 2 nuts tightened to each other to keep the disc tight but allow the screws to be aligned and tightened into the rim.

Seems to work well. The gap will be adjusted on the next ones, a bit tighter to the wheel. I calculated about a 2.5mm gap will keep the sidewall free of the discs for most tire deflections. I can always cut the rims to a smaller diameter later if there are problems with this set up.