This
Toe, Caster and Camber explanation might give you some more information.
If yours is leaning back towards the passenger compartment, it would be positive camber, which is what you want according the article in the link.
Is it true deathwobble where you could actually loose control, or just bad viberations with the steering wheel moving back and forth? Out of balance, out of round, or seperated tires can also cause violent vibrations. If you haven't tried it yet and want to before heading to an alignment shop, swap the tires front to rear and see if the problem goes away, or persists.
Does it go away over 55? I don't think death wobble is works itself out with higher speeds like a balance issue does
