If so, these will have to be replaced with trailer rated steel wheels as the original split rim wheels are not safe and no one will work on these. Do not try to adapt an automotive wheel as they are not safe for this purpose, even though a Bubble is very light.
The tires can be purchased at any good tire shop. Only use ST D rated trailer tires. Do not use automotive/ light truck tires. Carlisle makes a very good trailer tire and so does Goodyear.