I just think hyperinflation sounds funny myself
I agree, 90 psi is crazy hard, and you'd have to replace the whole car after it rattled itself to death. But going to max sidewall ought to be the closest thing to a compromise between OEM over cautiousness and hypermiling lunacy. I've ridden in a truck with tires pressurized to 80 psi, and it's unpleasant to say the least.
So according to that chart, no passenger tire manufacturer even thinks about finding out how a 50 psi tire inflated to 50 psi handles itself? And while I don't think there's a blatant conspiracy going on in the petroleum industry, I suspect the bean counters quietly dismiss anything that could lead to a loss in the quarterly earnings. If I were an executive of a tire company, i would likely do similar things to make sure i still sold a lot of tires. Heck, I'd sponsor tire burnout competitions. But to say that a tire manufacturer doesn't keep certain information to itself (such as longivety of tires at sidewall pressure, and how high they can go without blowing up) would be counter to common sense and ignorant of the issues of capitalism. (No, I'm no proponent of socialism, just there are occasionally bad sides to everything.) And why wouldn't a tire company allow and encourage the myth that tires past the placard pressure are dangerous?
There is simply a lack of evidence that 50 psi in a 50 psi rated tire is a bad thing.