[jiggysubman]

there was a thread started by myself titled "steering wheel shimmy" with the same exact problem. I tried various things, and eventually just took it the the local porsche dealer to have the tires balanced. Now they're perfect. The dealer claimed that most tire shops don't have the high speed super-duper balance machine that they have. They did my balance for free, but others have reported around $100 for it. That price is worth it, and once you get it done, they will do it as much as needed for the life of the tire.