Steel casters better than plastic for this use?

[Doc]

I'm buidling a shelf storage unit for the garage and am going to put it on wheels to make it easy to move for cleaning or any other reason I may need to move it.

Since this is going to be sitting in place on concrete for long periods without moving, I plan on using steel casters since I assume rubber casters wouldn't be a good choice that they would develop a flat spot over time, correct? I wonder if these hard plastic casters I see could develop problems with potntially a fair amound of weight sitting on them for extended periods.

Thoughts? Input?

Thanks

[Twayne]

Steel rusts, especially sitting on concrete. I use rubber; seldom have any problems, do shoot oil into the swivels once a year to keep them working well.

[Howard Beale]

I've used cheap hard plastic casters for EVERYTHING in the garage without any problems. Buy 'em at Home Despot or Northern Tools.

I think steel casters would only be useful for loads exceeding 500 lbs.

[RickH]

I built a large paint storage cabinet out of several new but unused kitchen cabinets, the unit is 8 feet by 3 feet by 2 feet deep. Loaded its well over 500 lbs, I used steel casters, have had no problems moving the unit to clean under it after 8 years.