shimmies

Hi everyone. I've been driving my husband's Nissan Altima coupe. We know for a fact that the alignment is off. The two tires on the passenger side of the car were completely bald and I had them replaced. The mechanic told me and showed me that the front driver's side tire was also in bad...

seems to start the death wobble at 45 mph, the front end wobbles like crazy. doesnt do it all the time, just sometimes. what causes this?

Ok 99 Dodge Ram 4x4 Reg Cab Short Box 5.9 360 Sport 2.5 inch leveling kit and 285/75/16 All terrains. I have a couple issues with my truck, i am still getting left to right shimmy when hitting bumps threw town( just gets worse at higher speeds and the steering wheel and truck shake) these are...