The sticker on the inside drivers door is set the alignment at those psi levels. After that you go by what the tire says on the sidewall. It will give a max psi cold.

I run Michelin LTX 265-75/16 tires on my 2005 2500HD
 

In my truck, the door plackard recommends 50 psi front, and 50 - 80 psi rear. The truck rode extremely rough, so I downloaded a tire pressure guide from Michelin tires. The pressure chart is based on axle weight and tire and rim size. My truck is about 7,000 lbs without cargo, and a 60/40 split means 4,200 lbs on the front axle, and 2,800 lbs on the rear axle. I use Michelin LTX, load range E, 265-75/16. The Michelin guide said I should be running about 38-40 psi front, and 34 psi rear. Once I adjusted the pressures, the truck rode like a Cadillac and it was great.

I now see many, many trucks in parking lots that show evidence of tire over inflation, the most evident thing being excessive wear of the center tread. I think the OEM sticker is misleading and potentially dangerous because it over-pressures the tires on an empty vehicle, which causes bad ride, inaccurate steering in a straight line, hydroplaning, and poor tire wear. I will use the Michelin guide pressures from now on. Too bad GM can't do the same.

I get the best tire wear at the factory recommended settings for the front and the rear tires. At lower pressures I could see after 5000 miles that there was excessive wear on the inside and outside edges of the tires.

Overall I trust the manufacturers' engineers over some guy in a tire shop. Think about it.

My problem with door decal tire pressures
 

GM typically shows one set of pressures on the decal. Those pressures are for my crew cab truck with an additional 3,000 lb load of people and cargo. If I'm just transporting myself (200 lbs), I have aired the tires for 2,800 more lbs than I'm carrying, meaning that the center part of the tread is getting more wear than the other areas of tread because there is not enough weight on the tire to keep it from bowing in the center. The previous owner told me he always aired the tires to 50 psi front and rear. After I bought the truck from him, I noticed that the tires were almost bald in the center tread area, with plenty of tread at the edges, plus it rode rough all the time. I got new Michelin LTX 265-75/16 LRE for all 4, then aired to 50 psi. Same rough ride. I found the Michelin tire guide on line that included several air pressure charts for RVs, Semis, and light trucks. I adjusted pressure based on my tire size and weight on each axle, and the difference was amazing. Better handling, excellent ride, better stopping especially on wet roads.

The chart is specific about pressures. Just get a good tire gauge and see for yourself.