I have a 2007 RT with about 7,000 miles on it. It has the 18" Goodyear Assurance 225/60's on it, and shimmies at 35 mph and 70 mph. Interestingly enough, the problem seems worse when the car has sit for many hours (or overnight). The problem lessens after about 15 minutes of driving, but does not go completely away. The shimmy is more noticeable at 35 mph, than 70. The dealer balanced the tires for me at 3,000 miles which helped, but did not totally clear up the problem. When I brought it back in just about a week ago, I complained again about the problem and really insisted that I wasn't going to take it back until it was fixed. Long story short, I took the service manager for a ride and demonstrated the problem, and after a long discussion convinced him that they needed to put four new tires and wheels on my car to convince me that the problem was not in the tires and wheels. We compromised on taking a new car out for a test ride. We searched the lot for the exact same tires and wheels, and sure enough, the last car we looked at had the same tires and wheels. Turns out, it also had the exact same shimmy! Seems that there may have been a bad batch of tires put on our cars. The problem has not been resolved yet, but they were going to check some stuff with the factory, and it looks like they'll be giving me four new tires. Will post again when problem is corrected.