It's obvious.........call a tire repair service to take care of the flat OR if you have a spare replace the flat tire with it and drive slowly to the first tire service or truck stop with tire repair........THEN...........invest in a GOOD tire gauge, not one of the .99 cent wally world specials, a possible TPMS system, without a doubt a good VIAIR air compressor, a membership to a roadside assistance program.
Check your tire pressure EVERY day before you take off. Visually check your tires on a walk around anytime you stop and are ready to take off again. If you don't have a spare.........get one, even two if you travel much. A couple of wooden planks, bottle neck or compact floor jack, 4-way tire wrench safety hi vis vest when you're out with a problem roadside. Safety triangles or battery powered flashing warning light. Depending on tire size consider LT instead of ST tires, buy the best set of tires you can afford.