Before changing tires I would change the rim tape. if you have a rubber or plastic strip replace it with Velox fond de jante. Also I would suggest inspecting your tires once a week and picking out the glass, flint, wire etc with a straightened paper clip. I do this on the theory that with today's quality tires it takes several days for the sharps to work their way through the tire, so I remove them before they cause a flat. Just wear eye protection because they can fly back at you.

If it matters - I use gater skins and am very happy with them.