This has nothing to do with ships, only a musing that I can't quite get to grips with. I take a car wheel and inflate the tyre to, say 20 psi, then I put it on the car and lower the jack. Does the tyre pressure stay the same due to tyre deformation or does it increase due to loading? If it does increase, would it still increase if I inflated the tyre hard? i.e. no "footprint" on the ground.