So, since nobody
could help, I simply ordered a cheapie 200x50mm tire with a rim and waited...for a month...gotta love Czech Post.
Turns out that the rim is a bit smaller and a lot narrower then I expected it to be, the inner tire rim is 95mm in diameter and 30mm wide. Developement continues...
The spokes are NOT the final version, as I still haven't decided on what to make this thing out of...
One posibility was 7075-T6 aluminium, but that would involve a lot of expensive machining (as you'd expect).
The other and ever increasingly more realistic variant is carbon fiber. For a part this small it will be cheaper even with the tooling costs. Now there's just the problem of having 0 experience with CF.
Anybody ever made a wheel of any kind out of CF?