They are tough wheels that will hold up in applications that softer wheels may be torn up in.
They have very good rollability, but can be abusive to floors and like other hard tread wheels, will have trouble on uneven and debris laden floors.
They are capable of taking high temperatures and exposure to water, chemicals, grease, oil, etc, however exposure to these things will accelerate rusting.
These wheels come standard with a grease zerk fitting in the hub. Silver paint is standard. Durometer: 95 Shore D. Temperature Range: -45 to +600 Degrees / F.