Didn't like my old bed frame. Right now I have a low carpet and it is vary hard to move bed with my plastic pads. It also has steel rails and the bed slides on them. To move the bed, I have to lift up at the steel frame and move 1 side 6 inches, go to other side and do the same. It is a real pain in the ****. I also have hit my shin on the sharp corner of the bed frame!
I decided to buy some pieces of wood (5/8" thick) and mount my existing wheels that I removed from my speaker boxes. It is best to use plywood and not particle board as screw may crack the wood. I did have to buy 2 locking wheels. My total cost $65 since I already had the non-locking wheels. The wheels are 5", and are 6" to mount ---- lots of clearance, actually a bit more than before. It is important to get soft rubber wheels, the locking wheels are nice and wide. Got them from Princess Auto.
Mounting the 2 locking wheels on opposite corners give it stability. Total of 8-9 wheels required. Now I have to unlock the wheels then just push the bed and it moves real easy! Mounted the 3 wood pieces crosswise and 3 wheels in middle row for stability lengthwise. Best to put wood lengthwise as well. They are mounted to wood in box spring with 2" screws. Used some silicone as a thread sealer.

 

That's using your noggin!

Put a drop of oil on both the upper and lower swivel bearings. A dap of grease on the axles will help too. It is unbelievable how many carpet fibers and hair get caught in there. In our laboratory at work we have about 40 tables with 4 swivel casters on them. The tables are about 35 years old.......