Would love to hear any ideas on what I experienced today. I have a 2011 CTS Premium AWD with 33,000 miles. I put new tires on it on Tuesday. On Wednesday, I cleaned the wheels using my Speedmaster brush so I could reach the dirt in the back. I did make contact with the calipers while doing the cleaning. No problems driving the car on Tuesday and Wednesday, although Wednesday was limited to backing the car out onto the driveway and returning it to the garage. Today when I attempted to drive the car, I put it into reverse to back out of the garage. The car acted like the parking brake was on or something was blocking the tires. I checked the parking brake, but it was not engaged. I got out of the car and looked for obstructions, but there were none. I got back in the car and turned it off. I started it again, put it in reverse and the same thing happened. I put it in drive, and the same thing happened. I then put it in reverse, pushed further on the accelerator. There was a noise, but the wheels broke loose and the car drove fine after that. I had the tire shop look at the brakes and they found no problems. There is no fluid on the garage floor. Any ideas as to what happened? Could it be a transmission issue? Thanks for your thoughts.