Incorrect toe will eat tires a lot faster than negative camber. When the toe isn't right it's basically dragging the whole tire's surface unlike the inner edge when there is too much negative camber. This is why an alignment needs to be done after lowering, both toe & camber changes. Like I said before if only lowering a small amount negative camber isn't a severe issue like it is with 1.75" or more, still toe needs to be corrected.