We went through the same thing, turned out to be a bad tire which couldn't
be seen until they took it off to rebalance it. When spinning on the tire
balancing machine at a fairly slow speed, you could see a rise and fall in
the middle of the tire. Upon taking it of the rim it was discovered that the
steel belting had separated right in the middle of the tire which they said
was a very dangerous condition.  EVERY tire sales person you talk to is
going to say it's your fault, "You must have hit a pot hole or under or over
inflated your tire, it's not a defect".  The man that looked at it for me
said it most certainly was a defect and to fight for a pro-rated refund.

I would very carefully check out both your front tires before you go any
further.

Good luck

John & Wendy
Cape Cod, MA

'85 Westfalia "S-Cape"
'98 Passat "The Doo Dah Machine"