Back in September I purchased a set of 4 new Scorpion Verde All Season tires (17"). I had the 4 wheel alignment completed at installation, then had them rotated at 6,000 miles. Now--9,000 miles later--I was informed by my Volvo dealer that 2 of the tires must be defective, and I should return them where I bought them. On 2 of the 4 tires (the tires now on the back but spent most of their miles on the front) are badly worn along the inside. The 2 tires now on the front are fine, although beginning to wear on the inside.

Unfortunately I bought them online (Tirebuyer), but I had them installed at Goodyear. So I took the car back to Goodyear. The checked the alignment and found that it was still perfectly aligned. They even asked me to obtain "official" alignment specs from the Volvo dealer, which I did and compared with theirs. No problems. They checked over the suspension and found no problems.

Goodyear is trying their best to document the issue and obtain warranty replacement or credit (unlikely), but how can i prevent this from happening again? My wife and I are not spirited drivers.

Front camber L -0.5 R -0.2
Front caster L 5.1 R 4.9
Front toe L -0.08 R -0.07
Total toe -0.15

Any recommended changes to alignment or tire pressure adjustments? Or different brand tire? Thanks so much!