Originally Posted by
horinorbi1993
Thanks for your input. I am afraid the 72.5 PSI limit applies only to Zipp and Hunt wheels.
As noted, the ~73psi limit is an ETRTO guideline; Zipp and Hunt aren't the odd ones out, these are standards that many wheel and tire manufacturers are building to. Just something to be aware of if you stray from Giant's own tires in the future.
Not that I think that any of this is the source of your problem. I don't see how something like faulty cores would prevent you from going beyond 40psi and the likelihood of two pump gauges being in agreement, while being so wildly wrong, is exceptionally low.
edit: one thing that you could try immediately, just to rule out the cores, is to remove the core and inflate to see if you still hit a wall at 40. All of the air is going to rush out when you disconnect the pump head, obviously, so be sure to keep the valve away from the pooling sealant inside.