with metal ones that is. I have had two fail where the rubber meets the brass tip. One was in Texas on the way to Colorado from Florida. Luckily I was stopped when it let go. The first was while changing air pressure for the trip. I think this is the problem, after multiple air pressure changes, you flex the stems and it weakens them. I replaced all of them with metal on my return home. I know others have had the problem as I did a search, just re-enforcing the issue. I also sent an email to Chrysler, got an automated reply.