DanG wrote:
Walter, if your tile does not go all the way to the ceiling use a
nail or small drill bit to find the studs right along the top of
the tile. The holes can be filled and hidden with a bead of caulk
once you find them. Once you know where they are you can plumb
down, though not all studs are perfectly plumb. I would make an
undersized hole in the tile to verify the stud, the escutcheon on
the grab bar will cover a small change. One or two very good
screws are more valuable than worrying about using all the holes.
Fill the back of the escutcheon plate with good caulk ( I would
not use silicone) to prevent water from entering the wall at that
point.

When I have done this for people, I find it works best to use a
bar that crosses 2 studs at an angle rather than just a
horizontal or vertical bar. It seems to offer more choices and
work for different height people.

Second the thought on angled bar.
My house came with such a bar and it is very useful.

Lou