Last night my tire was very low so I put 90 PSI in it planning to deal with it in the morning. This morning it was completely flat. After fighting with my stuff I finally got it pumped up and to the tire store. A bit later the tire jockey comes to get me and says, “You have to see this because we have never seen it before.” They were all standing around talking about it so I know it was something special. This was the rear tire and they said the other one was about to blow as well. Any idea what would cause this?