2011-11-05 Rubber Ball Bearings Inside Tire

Changed PR2's today on KrZy8. No complaint, nothing but kudos for these skins..

Central Kali --> Stowe Vt --> Salem Or --> Central Kali --> Lots o' commuting, and finally, these tires are toast.





But, when changing tires, found these little 'ball bearings' inside, at first thought wheel bearing failure.. But the size is too small, the number too many. And the wheel bearings are fine, thank you... 





These pix show tire inner side - the goop is lubricant..





I had noticed that when spinning the rear tire during daily pre-ride check flight, I could hear something moving about... and wondered if I had left some debris during tire install.. but I'm pretty careful installing tires so didn't think that was it..



Final shot 





Any idea? The 'ball bearings' are soft, can be fingernailed to death, indicating rubber.. But where did it come from? Anyone else have similar experiences?