Panzer Art Mercedes LG3000 Wheels

I recently bought a set of these for the ICM kit. While they’re very nice, the set includes a little bag containing a couple of things that look like they’re hubs. Except there are only two of the things - the front wheels have the hubs cast in place, and it looks like the rear wheels are meant to use the kit hubs because a) you’d need four of them and b) the rear hubs are molded into the kit brake disk parts. This just leaves the spare wheels, which mount to a couple of posts which have a bracket shaped like a Reuleaux triangle with a hole in the middle, with bolt mounts to fix the wheel to.

I’ve examined the photos and diagrams in the appropriate Nuts & Bolts, and I honestly can’t figure out the purpose of these. Anyone who has actually built the kit using these resin wheels know? I mailed Panzer Art but got no response and, since my first guess was that maybe I was to graft the hubs onto the brake disks, and I was missing two, so I bought a second set, and again just the two hub parts. So it seems there are meant to be two of them - but where are they meant to go? Sometimes I really wish they’d include even a basic instruction sheet…