From my experience firmly anchoring this kind of furniture on plasterboard
is not easy.
First many fitments have anchorage holes very close together, quite
impossible to achieve in plasterboard - so pick the right kind. Even then
something as sturdy as a grab bar needs reliable fixing and I would suggest
mounting it on a substantial wooden base that is first secured to the wall
Drilling into tile is not difficult, use a piece of masking tape to reduce
the masonry drill slipping and do not press too hard, just sufficient to
cut. Whatever screw/anchor you decide on it must not put any significant
pressure on the tile, or it will crack, I cut the tile hole slightly larger
than the mounting hole or this reason.
To use toggles requires a very large hole


The tiles are on the side of a shower stall, which is probably
made of plasterboard underneath.
I've got some spring toggles and some other expaning wall anchors.
Use a new masonary drill push the drill onto the tile until you hear a
crispy noise then you can drill your hole very slowly.Spring toggles
are ok but I use umbrella clips same principal but when you take the
bolt out the base stays in the wall without falling out.T.R.