In the past I've used Michelin Arctic Alpin. This year I went with Goodyear Eagle Ultragrip. I love them. They're H rated too so I don't have to slow down much. With my Passat, I did experience the feeling you describe. It turned out to be a broken upper strut mount. I would periodically feel or hear odd behaviour when going over medium to large bumps. Ask me about the 92 BMW E36 I totalled because I went cheap on tires....