Coming from an electronics and aerospace background I am always surprised and a little bit confused by folks on this board, who are apparently not mechanical engineers, second-guessing manufacturer's specifications and trying to justify exceeding published maximum limits. In my business maximum ratings are absolute limits, not starting points to see how far you can push things.
In the present case I cannot see how if the manufacturer says 55psi maximum that somehow 90psi should somehow be OK, tube or not. Before trying to overstress such a component I would think very hard about how much energy is stored in an inflated wheel and tire and the consequences of its sudden release, not to mention what would occur if you were on the bike moving at high speed at the time.
Do you really want to ask a bunch of strangers on the Internet if it's OK when the manufacturer says it is not?
Last edited by dsbrantjr; 10-10-12 at 02:10 PM.