As you dialed out camber, make sure your toe are still straight as they both go hand in hand. People often don't pay attention to toe issue because it's harder to spot (seen to the naked eye) than camber. But having a toe out issue (no matter how minute it may be) will kill your rear tires MUCH faster than negative camber! My first set of tires wore excessively on the inside and I too, thought it was the -2 degree camber that killed it. But as it turns out, my rear toe setting was only 0.5 degree toe-out. After having that zeroed out with the camber left alone at -2 degree, my second set of tires wore very evenly.