Tires Foam filled tires

[Grumpycat]

What do you mean when saying >>"they really need to sit flat", is that the whole wheel laying down flat on floor, horizontal?

Foam is in 2 parts (3 if you include nitrogen) mixed the moment before inserted through tire valve. Then it needs to set. If wheel is vertical it will have a flat spot.

The tire is filled vertically, with a hole drilled in top of tread to let air out as foam fills. Then something like a big sheet metal screw is used to plug the hole. Wheel laid on its side to cure.

I worked at a shop doing this in 1978. Would expect any modest sized forklift shop would have the service.