I run my tires around 80psi for highway travel like the dash plaque says. I agree that you shouldn't take them up to 110 psi if they're dried out.Thanks. Not sure on any dry rot. If a little dry rot maybe 70psi?
Like @Jbulach says, if you have a couple of buddies have one of them drive your dually in front of you and have the other buddy follow you with flashers and a "slow vehicle" triangle on the rear of their vehicle.