Pre-trip? What pre-trip?

That’s not dry rot, it’s where the outside tire blew out and the sudden weight increase split the tire.

 

It’s fairly common damage.
Could be a previous blowout and they only had one tire.
When I take a call for a tire, I always ask size and wheel type. I load up two tires and a wheel.
@SmallPackage may know what they call that sort of damage.

 

You have learned me something

 

Yes. That is lower sidewall bead stress damage due to heat stress from under inflation and overloading at some point in its life. That tire should be scrapped if it wasn’t. I wouldn’t have put any air in it if it was me. Big risk of zipper type explosion.