Tire wear, what's causing this! ? ?

Big B; Trying to press them in may not be the total answer.If the pistons appear to be flush with the casting then theres no point in trying to put them deeper. If, however they appear to be out of the bore by an amount similar to what you need, then its possible that theyre not seated. And if there is debris in there,it has to come out. It was fine for it to have been in there with the old pads because it wasnt affecting anything. Now however any debris in there may have lodged itself between the piston and its bore, during the parking of the piston. This could cause the piston to stick. But thats not the worst of it. You have to ask; "where did that debris come from"? Well 2 things come to mind. The first is knowing that flex hoses rot from the inside out, it may be rubber dust. The second possibility is rust.As you may know, brake fluid is hydro-scopic; that is, it has an affinity for water. It absorbs water from the atmosphere. This water, since it is heavier than brake-fluid and doesnt mix with it, collects in the lowest parts of the braking system, the calipers and wheel cylinders. The rust particles can be larger than the bore clearance, hence the sticking. But it gets worse yet. When temperatures fall below freezing the water freezes and the caliper may become inoperative. Imagine that scenario.
-There is one more thing to consider. If the master cylinder is FULL, and capped, it will not allow any more fluid to return, and the pistons cannot seat.
-You could perhaps try a pad set from another vendor to compare thicknesses.
-Also, I have had to file-fit some pads that were absolutely too thick. They file easily with a sharp coarse file,or emery paper. I use a caliper to make sure they finish flat, and parallel to the back-plate, within a few thousands of an inch. Break-in takes care of the rest.
-Oh yeah,and finally; the outer perimeter of the disc often accumulates rust scale, at a point just outside of where the pads ride.If you havent already knocked it off, that may be your problem. It can build up pretty thick, certainly enough to not allow the loaded caliper to pass over it.
-Happy wrenching