I hope this helps. Wilson sells-or gives to the buyers- smooth, metal, saucer
shaped discs with a small impression in the middle which the metal leg points
fit in. I am told by someone who knows that this is the easiest, and safest way to
move heavy speakers on carpet. If you have a hard surface they have a model
with some type of fabric on the floor side.
I use 4" vinyl coated wheels to move my speakers in place.
I know from others who own older "Tubby" speaker that wheels are
often employed.