I don't know if an adapter exists but if you find one be aware that an adapter will increase the distance between the caster swivel to the leg bottom, thereby reducing the maximum weight capacity. I am storing close to 75 pounds per shelf. I would not use an adapter for this much weight. If it is a lot less weight an adaptor should be Ok.
depends on if it fits your threaded insert and if the weight of the loaded box does not exceed the load rating.
Yes they can be used on carpet. No problem at all with grease stains. I’m very happy with them.
It's the size designed to fit the hole at the bottom on the shelves they are designed for. Thinking back, well just remembered where I put the levelers they were meant to replace and they are 5/16 bolt and I'm assuming and look like 18 thread, so, that would be a 5/16-18 standard. The threads are to course to be metric. Hope that helps.
might make it tipsy as CG would be increased
fit my standard metal wire rack shelf unit with the 1" posts having threaded inserts at the post base.
Two of the four casters have lever locking mechanisms.
To short to do the job correctly, about 1 inch, it should be at least 2 inches.