Just an FYI for you beach goers. One of my rear tires started ballooning really bad and came unbalanced to the point that you could actually see it at speed. So I pulled it apart the other night and literally dumped a pile of wet sand out! Pretty sure it happened from roosting through receding waves which happens to be pretty damn fun. Anyway, just a PSA for you dudes and possibly a mystery solved for the OP.