The reason a submarine can’t go but so deep because of water pressure is that the sub’s interior pressure can not exceed what the crew can tolerate.
If you bring the pressure of the inside of a vessel up to the pressure outside, the crushing forces are zero.
So although there are a lot of reasons tires will not work, pressure is not one other than one would have to inflate them with a liquid that would not freeze and to an internal pressure that would grip an oil soaked pipe.
That makes sense. Hadn’t thought of that.
I am sure there is a reason, but I wonder why ther was not some sort of shut off valve located within the BOP stack that could be manipilated by a ROV?