the real reason this happens is because like our counter part the Z the stock arms flex ALOT which causes neg/pos toe when your suspension travels up and down when hitting bumps/dips thats how you can have feathering on stock tires with no suspension modding. then when modding the tire is obviously at a neg camber and causes premature wear. Be happy you got that many miles out of the tires. I am lucky to get 10k on a set of tires after flipping them. 10k is 6 months of driving.