Age of contacts for recommendation letters for tenure-track position I finished my PhD last month and now I am heading towards a non-tenure track position this year.

In a couple of years I want to apply to a tenure track position. The recommendation letters may be a mix of old and new - but I wonder what mix is most recommendable, if it matters to the committee at all. I would strongly prefer to give only new contacts for letters of recommendation. 

What are your experiences, in particular, if you have been a search committee before?
The letters should all be new, even if they come from old contacts.

In particular, if your PhD advisor writes a letter, they should write a new letter.  Of course it can be a revision of their old letter, but it should include language about your more recent activities; otherwise, it gives the impression that your more recent activites are not significant enough for them to even notice.

As for the mix of old and new references, it doesn't really matter, except for yourPhD advisor.  You should choose whatever references will paint the best picture of you as a tenure-track faculty colleague.  A missing  advisor letter is generally a red flag -- it's part of your advisor's job to advocate for you on the job market, so if they don't, there must be a reason, and it might be you.  But that can be offset by sufficiently strong letters from others, and it matters less and less the longer you've been out.

(I have been on faculty search committees for many many years, including three years as chair.)