well...... ran outdoors for first time. loose dirt / gravel. the large hole in the associated wheels allowed the rears to FILL with dirt and small pebbles. have holes in tires also but rocks are under foams. brand new set of caliber 2.0's and blue closed cell foams. will be cutting apart to remove rocks and glue back together. heard other guys claim their tires are ruined after getting rocks in them. however I have used this technique in the past to replace foams on otherwise good wheels/ tires. will document this process with pics if anyone is interested in how to save your tires.