Thought this might be helpful for some. When I had my wheels/tires mounted/balanced, the installer also placed the center caps on the wheels. Later on when I was washing my car, I noticed the center caps were super loose and easily removable. Of course I would have not even noticed until I took a closer look. Luckily, they did not fall off while driving! So after some inspection, it looked as if one o-ring was simply not positioned correctly. Keep this in mind when you get your wheels installed and make sure your installer shifts the o-rings to its proper position:
