I forget that alot of people drive their truck around empty, I use mine for work. It always has about 500 lbs in it minimum, so that is why my tires are just under the max pressure. You guys are right, if I was running empty then I'd probably drop my pressure a smidge too. My bad.
Also had a friend that had a warrentee turned down because of over pressuer, his were inflated to max at cold. When they checked them hot he was like 7lbs over.
When I had my 3/4 ton it called for 80 psi too, I ran them at around 65 most of the time but pumped them up for a load.
Anyhoo I still think 35 is way too low, that would probably make them wear on the outside more than the center. I think you are on the right track to air them up a tad......and the tire store guy is wrong. IMHO