would you be able to post a pic where it says the minimum psi on the tire? I work with tires and wheels and I have yet to see a tire with a range of psi like what you're describing and I'm curious to see.
I would set the pressure to what is listed on the placard.
usually with an 8 ply passenger tire, you shouldn't go below 20 psi.
they're for the technicians mostly. basically safe maximum levels to get the tire installed on the wheel and other safety information. sometimes you really have to inflate them when installing to get the tire to seat properly