New tire will not remain inflated?

Who manufactured the tire, where did you buy it, and, how old is it? Is it a 1st quality tire, a second, a retread, a knockoff? I would go back to the place that initially sold/installed it to start. Previous remarks about defective valve stems, possibly defective beads and/or casings or damaged (bent or out of round) rims are valid. Some manufacturers permit the installation of tubes in tubeless tires however you need to make sure you don't have other safety issues first. I've never seen a steel rim with porosity but I have seen cast alloy rims with porosity that leak air.

These issues can be very frustrating however patience is the key.

Chum lee