Auto tire deflate/inflate

I would like a dash button that lowered my rear tires for daily driver use or raise hauling loads. Better yet a knob or sliding bar, that let one set the pressure. Every time Costco rotates my tires, I have to sit there and let the rear back down from 80 PSI before driving off their lot. I have even showed them the pressure chart that at 45 PSI the tires have a 2470 lb capacity, 4940 for a rear axle that weights around 3300-3500 pounds. No go sir, door jam says 80 pounds for rear tires!!!! And I say, do you think the rear axles is at it's rated 7,000 lbs right now???