[DJ_BigC]

Now seeing as how you had an alignment done and the tires are still cupping is telling me that the alignment is/was probably done wrong or the factory alignment specs with regular wear and tear on the car are causing this to happen.

Next time you get an alignment done, post up your specs or PM them to me and ill tell you what/why everything is happening.

No matter how expensive or how cheap a tire is, if the alignment is 100% true or even slightly modified/enhanced from factory specs, you should get perfect tire wear, even if its a 5$ tire, now how long that tire will last will be the issue.

Now for cupping tires, usually camber+toe can/will be your issue, strictly toe will wear a tire evenly but very very fast and cause a pull, toe is your heaviest wearing angle, incorrect camber and toe will wear and cup a tire, camber also pulls twice as hard as caster. 80% of GM vehicle get really bad cupping front tires, some rear tires because of bad factory alignment specs or sagging suspension components. At that point tire rotations usually just cup all the tires all at the same rate so you dont notice it as much.

Next time you get an alignment done, make sure the tech checks the front end properly, if its all tight, then get a GM dealer to align your car. The tech may have to modify and play with the specs in order to get everything lined up just right to prevent future tire issues. But remember suspension components do sag with time (front strut assembly's for one) but the rest of the main components may be OK, you need to make sure they measure trim levels and ride height of your ca, to make sure that is within spec.