Specialized Wheels

[Jnadke]

You might be focusing your search in the wrong direction. Try searching for a keyway hub with a pneumatic tire instead.
Rarely will you find a wheel with a built-in keyway, but a hub is a separate attachment that provides the appropriate shaft connections (usually bolted onto the rim).

GoKart tires might work. Check this out...


Better yet, look at this. The moped tire (2 1/4" x 16") would work perfectly. Then get the Keyway type hub on page 8 for it.
Now where to order...

From the looks of it, your best bet is going to be 80's/90's era moped tires. Those are usually the large bicycle-style tires you're looking for. Most modern mopeds have those midget tires that are useless to you. You should be able to find a moped tire with a rim that has bolt holes. Check your local junk yard(s). The only problem is finding identical tires...

You can always make your own hub to bolt onto the rim. Either machine it out of aluminum, or you could take a keyed steel gear, and find someone to weld it to a 1/8" steel plate. Then calculate and drill the bolt holes and drill out your bore (plate only!). It's a poor substitute, but it should work fine for prototyping purposes... Of course it's easier said than done, the hard part is lining the bolt holes up so the shaft is dead center...