OK, so the OEM tire is just too skinny for the size of this car and perhaps you want better traction and a wider tire. You also want to keep you OEM wheels for a while and not change your rims. Here's the ticket - these Ultra High Performance All Season tires:
BF GoodRich g-Force T/A KDWS in size 245/55WR18
This is the perfect upgrade using the OEM 18x7.5 rims. This is the only tire I could find in that size. The OEM tire of 225/60/18 (28.6") and the 245/55/18 (28.5") are the same height. This car is very difficult to upgrade due to the tall tire OEM tire used. The OEM Continental Tire is a Touring Tire.
Only $104 each at TireRack.com .