Awhile back I removed a set of BF Goodrich Radial TA’s from a set of 69 XT wheels because one started a bulge out place on the sidewall. They were old but perfect thread. The tread is what most people pay attention to not the condition of the sidewalls.

The steel belts start to rust internally after a certain amount of time on the radials.

Radials delaminate.

That can happen with bias ply tires as well.