My rule of thumb has always been to inflate 20 psi above the marked pressure. I do that for two reasons, I am heavy, and I like to reduce pedaling effort. Now I can not guarantee that will work OK for you, but I have never had a problem and I have been doing it since the early 1950's.
I would like to point out that you can not blame the manufacturer though if something fails when you are using it beyond their specs.