Had an errand to run today - needed to be extra sure I wouldn't get held up by a flat. Rode my 3 Speed with toughies instead of the delicate little tubulars.
Of course I got a flat. Big old chunk of glass. Repairing it, I realized that it punctured the tire right exactly where the toughie overlaps itself. Sure enough, the hole went thru two layers of toughie on its predestined trip thru my tube.
Makes me wonder - maybe I should just get some thin aluminum strips and stick them in there. Toughies are useless against pointy stuff. Maybe a thin layer of actual metal would do more good. Toughies just seem to me some plastic. You can cut right thru it.
That reminds me of a ride about 10 years ago. I ended up hitting a pile of razor knife blades. It sliced my tire bead to bead. It went right through my tire, toughies and tube like they were butter.
Your glass chunk was probably like those razor blades. It sliced your tire, not puncturing it. There's not much that will stop that. Toughies are there to prevent punctures, not slices. Nothing will do that. Your aluminum strip idea will probably prevent a total slice, but will probably backfire on you. The strip will wear on the tube and do the exact thing that you are trying to prevent. The edge rubbing against the tube will probably slice it. Even if your strips prevent a slice on the tread, glass can slice the sidewall quite easily. It's just one of those things. My toughies have been very worth it even if they didn't stop the razors. They did prevent a puncture by a 1/2" lag screw stuck in my tire.