[rotorwrench]

Very few casters of smaller diameter have ball bearing wheels/axles. The bearing type axles are generally much larger diameter than the ones they use on the car dollies I've seen. We used large diameter casters with polyurethane wheels on our helicopter float and they lasted about 5-years before they all disintegrated. Cast iron or cast steel will outlast the caster swivels but they don't roll near as easy as the ones with hard rubber, plastic, or pneumatic wheels. Any casters with plastic wheels should be made of nylon or delron so they can take the load and last a while.

I can about guarantee than most casters aren't made to last a lifetime anymore. There is always a weak link somewhere.