posted June 16, 2003 06:15 PM
It doesn't look like anyone is going to respond, so I'll give it a try!
I'm going to translate your dimensions into English units, since it is easier for me (and perhaps others).
We are dealing with a 5 year old car being driven 4,000 miles per year. That's not a lot and I would hope you are doing the manitenance according to the time elapsed, not the mileage - meaning that oil changes, etc. are taking place about every 6 months.
If you drove 15 miles home, then I don't think your tire was flat when you left the dealership. First, I would think you would have turned right around if you heard the "pebbles" noise immediately on leaving the dealership. Second, running on a flat tire will destroy it in much less than the distance home. That leaves 2 possibilities: 1) The tire picked up a leak on the way home 2) There was a slow leak when you left the dealrship and it didn't reach a critical point until you got close to home.
When the dealership examined the tire the next day, they were probably looking for a puncture, and since they didn't find one, they pointed at the valve. What they didn't know (or couldn't explain) was that about 10% of the time, tires that are run flat obscure the puncture in the sidewall, because the evidence is destroyed.
So what could have happened at the dealership that could cause a slow leak:
1) In the process of doing a rotation, they could have damaged the valve. Possible, just not very likely.
2) The valve core could have been nearly loose and filling the tire with air could have loosened it enough to slowly leak. Even less likely than #1
That leaves us with picking up a puncture on the way home. As coincidental as that sounds, that seems to my eye to be the most likely.
I think the dealership used the leaky valve as a way to gracefully deal with the situation. Yes, leaky valves are not uncommon, but punctures are very common.
Yes, I am sure you don't think you ran over anything, but it is also fairly common for people not to see the thing that caused the leak (Hint: Otherwise they would have avoided them!)
Hope this helps.