2009 Dodge Ram 1500 wheels problems

I had the tires rotated at 7000 + miles, when I got the truck back, I noticed a slight vibration. As time went by the vibration got worse. I took the truck back to the dealer, in ft. Pierce six weeks later but because I drive a 1,000 miles per week, it hat 13,000 + miles and they said it was out of warranty. I took the truck to a private shop and they found the rear brake rotors warped so they turned the rotors and balance the tires. It was better but still had a vibration at interstate speeds.

April 18, 2013 at about 4:30 pm, driving on rt 400 expressway south, with my son in the passenger seat,the low tire alarm went off and I proceeded to the nearest exit, and pulled into a parking lot. Upon inspection, my front passenger tire was completely flat. Had tire changed to spare. On following monday, took tire for repair to my mechanic, where he found the valve stem inside the tire. The threaded collar that goes on the valve stem to help hold it in place was completely gone from corrosion.