I've never seen an inner tube with a pressure rating.
In any case it's irrelevant since the inner tube is just a balloon with a valve. At anything above 5 psi or so it'll stretch to fill the tire or whatever else is holding it in. It's the tire that provides all he structure, which is why tires (tubes) blow out if the tire isn't seated right or has a cut.
So it's he tire's pressure rating that counts, but even here there's generous margin for error.
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