Gerald spotted these unusual tires. The theory behind these tires is similar to the “Sawdust tires” that were produced and sold a couple decades ago.  Sawdust tires were recapped tires with sawdust (sometimes walnut shells were used too) embedded within the rubber mold so that as the rubber wore, the sawdust was exposed.  These tires were only good for a year, but according to internet reports, worked quite well. Apparently, they were also much friendlier to the pavement than studded tires, though studded tires work better.  Here’s a brief thread about them.

According to their history, the Green Diamond Tire of North America arrived in 1999.  As of 2009, the company is under new management and seeking to build a manufacturing location in the Western US.  Probably one reason for the Western Location is that a large number of Big O Tire retail outlets are selling the tires in Colorado.  The company’s western headquarters is currently located in Denver.