About 20 years back I upgraded one of my Snap On roll cabs to oversize urethane casters, I cut a huge one piece 1/2 steel plate to cover the entire bottom of my KR1000 box, then I drilled and tapped it to accept the new 8" urethane casters from a well known brand. They were hard gray composite wheels with burgundy urethane treads. About 10 years ago I noticed that one of the wheels had lost a section of the tread, it just crumbled where it sat, within a month, every single wheel had lost all its urethane tread. The boxes no longer get moved around, so they just sit on what's left of wheels minus the urethane 'tire' or tread. The next time they get changed I'm making steel or solid aluminum wheels, no rubber, no urethane. Changing casters on a box that weighs over two tons loaded isn't any fun.
I changed the original casters out after a few got torn up being rolled in and out of the shop across rough pavement outside. The new larger wheels made the boxes stable, but since I retired they just sit in my garage.
New wheels for the existing oversized casters are on my list of things to make, I'll probably just go pickup a chunk of 8" aluminum bar stock and go to work on the lathe making some wheels, but using aluminum will mean making a custom bearing surface in the center for the double row roller bearings. Using steel would eliminate this. If I can con a buddy into letting me at his CNC machining center for a bit, I'll make something really custom. I'm thinking custom 8" wheels, with a press in sealed bearing, plus maybe some sort of nylon or HDPE tire section that won't dry out and crack with age but I'm leaning towards all metal so they don't flat spot when they sit.
Even the hard plastic wheels on my older KRA boxes got out of shape over the years from sitting, the bearing area elongated and the portion of the wheel flat spotted.
