A newer tire set covered in E6000 adhered shoelace was indestructible & broke 280mAh/mile.  Alignining the wear point on the shoelace seems to be the key.  The next step would be common nylon straps, then kevlar, which would be military grade.  They're not wearing out fast enough to do meaningful testing.  Together with the shapelock reinforced wheels, it's become a truly durable system.