Here the link to PDF of Goodyear.
End of first page and whole second page is about that psi+10 and even for truck tires 20 psi extra allowed.
Mind that this is old information and Goodyear chanched their view about it lately.
But already in the beginning of my tirepressure-story I got a PDF of Semperit/Continental in wich standing still the tire is allowed to have a pressure of 1.4 times AT-pressure ( again not max pressure) to give it 2 times the maximum load.
This would mean for 50 psi C-load 70 psi and for E-load 80 psi = 112 psi cold.
When this 1.4 times AT pressure filled at freesing point of water ( 0 degr C/32 F) and incidentally by the heat of brakes the tire inside temp rises to boiling point of water ( 100 C/ 212 F) the warm pressure inside tire would be about 2 times AT-pressure.
Once read that tires are tested to be able to stand a pressure of 2 to 3 times AT pressure before they blow. So even filled that high and warmed up its still save.
A already damaged tire by to much heatproduction ,so to low pressure for the load, will blow sooner if filled to that high pressure.
Edit: reading back your first comment here about not to exeed the rimms maximum pressure, this also is sayd in the pdf of goodyear.
If rimm says 80 psi max pressure , realise this is also given cold, so when inside tire temp is outside tire temp , and about 18degr C/65F to 20C/68F.
so again then the rimms are tested for the pressure rising to probably 212F/100C.
Sometimes only maximum load on rimms is given.
my idea of reason for this is next.
When max pressure of rimm, then to high pressure pushes the rimm edges that hold the tire apart or bend them .
When to much load on rimm, the rimm is deformed by the weight on it, or goes leaking air troug it.
I would rather risk a rimm deformation then a tire blow out.
Most likely the pressure given on rimm is already conservative so cold pressure can even be a bit higher before damage to it. Also counts for weight.
When rimm would leak it is slowly and mostly gives time to notice it and handle to it.
But when tire damages by driving, you dont notice it that easy , and when it blows it can even cource accident.
I know this is a dangerous conclusion of mine, but yudge for yourselfes.