I noticed my '94 deville doing something funny,but only when I'am going between 65 and 70 mph. When I brake the steering wheel shakes up and down only very slightly and stops when I get to around 65mph. Its dosen't pull to either side when it does this and it dosen't do it at any other speed while braking. It also don't hear any noise of any kind from the front end. I did have a tire put on at walmart when I got a nail in one of my right front tire and noticed this tire is narrower than the continental brand tire on the left,could this be the cause of this? I also noticed that the bumps feel rougher could I need strut up front maybe thanks.