i will check that out.

i spoke to a guy at the local bike shop that has been riding for about 30 years and he said its very possible that when the tire was aired up, the person airing it up was pushing the valve stem out by pushing on the tire so that they could get the nozzle to seat and that maybe they pushed it out enough that it allowed the tube to get under the ends of the tire and it pushed the tire up enough that with centrifugal force pulling the tire outward, it pulled enough that the tire popped off the rim.

this sounds logical to me because when i put the new tube in the rim, the area around the valve stem keeps being pushed out of the rim and i couldn't get it to seat evenly around the rim. i thought it was just a cheap tire but it appears it could just be an improper way of airing the tube up. i will find out today because i am going to deflate both rims, check out that piece on the inside of hte rim, and then air the tires back up using a hand pump instead of my compressor.