2005 Deville knock from frnt pass tire

I have a 2005 Deville with 106,000 mi and i have had a strange, so far unsolvable problem. In cold (texas cold - below 70F) i will get a tap or knock from the front passenger side wheel/wheel well. It is only when the the steering wheel is about 5 to 10 degrees turned to one side (sometime left sometimes right). the knock will match the rotations of the tire, when i speed up it speeds up, but it doesnt nec get louder with higher speed. it does not do it all the time, it will just do it sometimes when its cold out. i have checked the cv joint and it is tight, the brakes and rotor have been replaced, and everytime i get out of the car to listen for it, or have somebody that knows about cars ride around it wont do it. I have decided to just wait for something to break instead of replacing the entire front right side of my car. Any ideas?