Cupping is often a balance issue. I doubt the shocks are shot at that mileage, which can also affect that. Alignment is what usually causes an edge to wear out first, although under or over inflation can hit either the edges or middle if way off. One thing to do periodically is to rub your hand over the tread first one direction, then the other. If you feel a feather edge in one direction, the tire is scrubbing rather than simply rolling and is an early indication that the alignment needs attention. You can usually feel this long before the wear gets too bad. A good thing to do when checking the tire pressure, which is recommended monthly.
The actual recommended inflation pressure depends somewhat on how heavily the vehicle is loaded, and your average speeds. Radical changes in elevation can also affect tire pressure, but most people won't experience that issue and if simply going over a pass, not worthy of attention.