Purchased a 2009 Yukon Denali in February 2009. Took the vehicle in for regular oil change and tire rotation. Earlier this year, we found that the left front tire was wearing we had to buy a new tire and had a front end alignment done. Went in yesterday (12/29/2010) for another oil change and tire rotation and have encountered the same problem with the left front tire wearing down to the steel. We had to purchase another tire for the left front wheel. The service department keeps insisting that we only need a front end alignment. We should have to buy two new tires within one year.