Requesting help: measurements of the DiyEboard.com airless 6" tire

I’ve been trying to get in contact with them the past two days to no avail. Is there anyone out there that could measure their wheels so I can figure out if it will fit my build? Expensive mistake if it doesn’t end up fitting. I’m attaching a quick sketch added to their official documentation. InsertPic_617F

Side question, is the core of the wheel center mounted? As in, are the bearings offset to one side or another relative to the tire on the wheel with the pulley.

Thanks to anyone who can help me!