Strange thing happened today. I had the tire taken off to clean the rim because it was leaking around the bead. The owner came back to me and asked my why there was sand in the tire. I told him I had no clue and that I hadn't touched the tire since I bought it over a year ago. He showed me the pile of this gray/bluish fine sandy material in the bottom of my tire and the rim was coated in it. No idea what it was. My only guess is that it was sand blasting material left over in a compressor line that someone then used to refill the tire with. Anyone have a better guess?