Briefly:

--The piece of debris at launch struck near the left-hand gear door, and either broke off tiles at the door edge or deformed the door.

--When reentry started, a small, very hot plasma burnthrough into the gearwell started. Temperatures rose slowly. A few other tiles began flipping off into the slipstream.

--Wires began to melt through from sensors. The lost tiles and/or deformed door increased drag on the left.

--Over Texas, the left gear tires exploded. This blew the gear door off, and the aerodynamics went totally to hell. The Shuttle rolled sharply right, and broke up.

I protested that the gear would certainly have an overpressure valve. He replied that such valves were intended to protect from overpressures on landing, and venting into the gearwell would probably have the same result. Or that the heating overwhelmed the valve, or melted the tires before the valve could sufficiently vent them.

Without more details on subsystems, I can't verify this theory. Input?