Q: Do torsion bars weaken, i.e. 'sag' over time, requiring that their preload be adjusted to maintain correct suspension geometry?

My '06 K3500 SRW came with oversized rubber and no lift. In the ~40K miles I've since put on, it seems like the front tires are more prone to rub when turning sharp, backing out of the driveway, etc.

Wondering if the torsion bars are the variable?