Just found this on my new 35" duratrac spare tire. I have no idea what it is. It looks it could be dry rot. But how?? This tire is brand new. Also, it has weird rust colored spots where the rubber seems like it was burned/melted/corroded. Upon touch, the rubber that is affected in those spots seem dry and brittle, with tiny flakes coming off on my finger.
What is this, and what do I do?