I blew most of the day today trying to make this parametric.  (aka.. change any variable and every part of the model adjusts properly).

I have failed thus far.

The intersection of the cylinder sections and therefore the filament holes generated from them, aligned to always hit the center of the rim area, relies on a lot of different variables.  I've accounted for most of them, but I'm still missing something.

Right now you can change the hub radius, hub height, rim radius, rim height, bearing radius, bearing height, depth of the hub inset, tire aspect ratio, and the tire overhang and have the resulting model be within half of the thickness of the rim for the filament holes.  But it's not perfect.

I'm going to stop right here and move on to adding the #MPRT - Modified planetary robotics transmission  to this now.

I've posted the current code for this.  if you can think in 3 dimensions and geometry is your thing, and you care enough to figure out what I'm missing... feel free to comment.  :)