I'm not a mechanic (nor do I try to be), by my experience tells me that if your tires are cupping it's probably a pressure problem more than an alignment problem. Usually you'll see an alignment problem two ways; one, the front tires will wear on one edge or the other due to dragging down the road vice rolling true (the outer or inner tread line will wear quickly) or; two, your truck will pull to one direction or the other when you let go of the wheel on a flat, straight stretch of road. Line your front tires up straight ahead while parked, and see if your steering wheel is centered or if it is canted to one side or the other. If it's not straight, you may be out of alignment.
