This is only noticeable at around 70-80mph. I shouldn't really go that fast but it's kinda hard when you are constantly wondering why your car is shuttering! It feels like it could be somewhat dangerous and I am going to get it checked out, id just feel better having an idea of what it could be before I go in, so I don't get screwed with cost. So when the car gets up to that speed it sounds like taking a wrench and putting it inside a small can and shaking it back and forth, sort of like a shutter or clinking noise or back and forth motion. It is quite loud and I can definitely feel it all through out the car. It reminds me of a tie rod or wheel bearing but I don't know the difference in noises. It sounds expensive and I hope it's not. It might also be an unbalanced tire, but it sounds way too metal-like for it to just be a tire. Thanks for any help!!