Originally Posted by Airdale
Let's clear this up a little. Are you saying a tire being operated in a "run flat" condition for 1800 miles could not be damaged to the point where it would suffer such a tread separation?
Never said anything about being "run flat".
Sidewall flex failures as seen in this picture
are the normal condition you end with after running significant under-inflation ( -80% to -100%) of the air pressure needed to carry the load, while driving at highway speeds .
Tread separations which is what we see in the subject tire have a variety of causes. Some can be traced to design and compound specification, some traced to factory process and some to long term underinflation (-5 to -205% or greater ) and/or significant overload.
As you know the load capacity is controlled by the inflation so sometimes you can have 100% of the sidewall inflation but 130% load. Other times you might have only 70% of the tire max load number but are running -50% of inflation.
Technically "run flat" means 20% or greater inflation loss from normal for that vehicle.
It is possible that the tire might have been run -15% for 1800 miles at relatively high speeds and stored in full sunlight so the excess heat broke down some of the rubber bonds but i would need microscope and chemical analysis to confirm that.