Originally Posted by haasman

If it were my car I would take it back and double-check the front wheel balance. Did this just start right after the new tires and alignment?

You could also rotate tires from front to rear and see if the vibration travels with the wheels/tires. If it is clearly from the left front, you could simply rotate the left side wheels/tires.

In my experience it could also be your steering dampener which is easy to check: Take on end off and compress and extend. It should offer resistance in both directions.

Someone once told me that any vibration over 80MPH is always tire balance.

Keep us posted,

Haasman