After I purchased my 2016 two years ago I bought a set of Aluminum valve stem caps with the smart logo. The first year they were on the car, it was stored in the garage. During the second year the car resided outside. Recently the low air light came on. When I tried to remove the caps they wouldn’t budge! Even soaked them for days with penetrating solution but no go. Checked with the local garage I use for some things and they said it was a problem in the past for them and they no longer install such caps on wheel and tire packages they sell - plastic caps only. So, after removing all 4 wheels, drilling the caps to allow removal of tire valve, breaking the tires from rims and installing new stems I can finally add air to my tires. Tires were also rebalanced. Only cost $42 to be able to air up tires! The shop guy said they were the type stems Chrysler uses. I’ve had a similar set of caps, but made of SS, on my old Benz and never had an issue.