I started to get a strong vibration at anything over around 50mph from the back end. I was running GoodYear 225/ZR17 Eagle tires. So I took them to get them balanced. The left rear tire wall was comming apart on the inside! The tire was less than six months old.
The GoodYear guys not only replaced the tire but replaced the rear right to give me a matching set. They put on a pair of GoodYear Eagle GT 225/45R17's. Pumped to 32psi.
Oh my god! The ride is 100% better! I'm gonna get a pair for the front next month.
Great above and beyond service from my local GoodYear store.

 

Make sure to get your alignment and lower rear control arms. There is something that caused that wear on the inside of the tire and it will just happen again if the root cause isn't fixed. Would hate to have you spend money on new tires again so soon.