I received a notice from Discount regarding a bad supply of Dill valve stems. They're (you're) offering free stem replacement which I think is stand-up and appreciated. A couple of questions though - the letter doesn't reference which tires I bought. I've purchased tires for my Cobra, my former E150 van and my daughter's '98 GT. How do I know which ones may have the bad valve stems? I purchased all of my tires in Dallas, Tx, but have since relocated to Las Vegas and somehow DT has my new address. As a tire dummy, how long does it take to replace just the valve stems? As I try to remember, the tire doesn't have to come off, it just has to be deflated? I plan on taking the Cobra in, probably next Saturday but any other info would be appreciated. TIA.