The rating is a limit, not a guide. 90PSI sounds bloody uncomfortable for days in the saddle. I don't find I get much pressure loss unless it's over months, but that's probably cos i run them tubeless.
I don't have them at 90PSI by the way. I just wrote that so people knew the limit.
I tend to get a fair amount on other bikes. All running tubes. Cheap tubes maybe?!
Top rated on the tyre itself is 90psi.
I'm unlikely to pump them up during a 9 day tour. So I'm thinking set reasonably high to allow for pressure loss.