general problems of the 2010 GMC Acadia

Tires cracking between the tread when they haven't been on the car two years, read that goodyear tire company had this problem with some tires, but do not see mine listed. Fortera hl 225/65r18 4bxn ardr 2813 ? I was told these are not safe.

Within a month after buying our 2010 GMC Acadia the front right tire was continually going flat. We were constantly refilling the air on a weekly basis. Took the car into the dealership to have it looked st and the couldn't find anything wrong with it on more than one occasion. We used fix a flat and continued to refill air and it has gone longer periods without going flat although tire is constantly low. Took the car in to dealership July 2012 to have oil changed and serviced with tire rotation etc. When I was driving home with 3 of my kids in the car, going 65-70 on the freeway the car started shaking. It wasn't the steering wheel but the whole car itself. It felt like one of the tires was going to fall off or the engine was going to fall out of the car. I checked the tire pressure and the psi to that tire was the same as what it was before I dropped it off for service, so the dealership didn't fill the tires but I knew I didn't have a flat tire either. I took the car straight back to the dealership on my way to work in the morning. They told me that the tread was separating from the tire and I needed a new tire. I think it should be covered under warranty as this had been an ongoing problem since we bought the car and have complained to the dealership multiple times. Just because they couldn't fond the problem before doesn't mean there wasn't a problem before.