Ok I found one article in the January 2014 Motorhome Mag under the tech advice section, I tried scanning and attaching but it didn't work so heres a quick break down of question & answer.
Guy went to Les Schwab for tires balance & psi check,Les said to run tires at 90 psi instead of the 120 psi marked on tire.
The tech guys answer is; Their right in suggesting the lower psi," The psi molded into the sidewall is the tire manufacturer's" MINIMUM PRESSURE" when the tire is "CARRYING it's MAXIMUM RATED LOAD"
I knew I read something to the effect i just couldn't remember exact wording
Oh & lets make sure we're talking the same thing, I'm not talking tires on your car's or 1 ton trucks or short busses, i'm talking over the road truck & bus/RV tires