It is difficult to attach a grab bar to ceramic tiles, because they are not strong enough to hold the weight. A metal bolt attached to the steel stud will not hold very well either. This is one of the reasons that I like to install plywood under bathroom ceramic tiles: grab bars can then be securely attached anywhere on the wall. There is a solution to the steel studs, however: toggle bolts or molly bolts can be inserted in holes drilled through the steel stud. Their wings will open up on the other side of the stud, holding the grab bar securely in place. The only problem with this method is lining up the drill with the steel stud. Make sure that you are positive about the location of the steel stud before you begin drilling. Use a drill bit with a carbide-tipped head to drill through the ceramic tile, then switch to a metal drill bit to go through the stud.