I think the "or equivalent" applies, but Wolf didn't bother to state equivalent to what. My guess is equivalent in durability or resistance to fracture supporting the high pressure exerted at the bottom of a caster, which, depending on durometer of its wheel material, provides only a thick line area for weight to be supported.

If your tile is supported by a cement without voids, its fracture resistance is probably high enough. You may wish to have the tile manufacturer comment. Alternatively, a spreader made of steel plate could be used. A few square inches might be enough. I use a sandwich of stainless steel sheet over thin hardwood plywood under the wheel paths of my SZ to protect my cherry kitchen floor.