My 2007 still working, but I should get new tires and although I'd prefer not to spend $100+ on new TPMS, I'm thinking these are about at the end of their life. I also got a set of wheels off of a 2006, same story, probably replace them when I mount new tires as well.

 

5 to 10 years is a normal life span. It's a good idea to replace them when replacing tires, at 5 years or more. valve stems are normally changed at every tire replacement at 5 years or more.