Note that the OP was asking about tights, not shorts and I personally stopped buying the PI bib shorts as they got cheap and eliminated the seamed edge on the shoulder strap. Now I find the strap just bunches up into an uncomfortable band. I decided to spend the cash and I use Assos now.

@OP. FWIW, it just sounds like your tights are stretched out and are done. I had no luck funding a bib tight that was just simply a lightweight lycra with no insulation. I gave up and just started using my leg warmers instead, which do the same thing essentially. I do like my Pearl Izumi tights that have a medium insulation, they are warm down to 30F or so and I'll wear at temps below 50.