Over the past few days I have been having a problem with my car. A few days ago I was driving at around 40-50mph when I felt my steering wheel become a little loose, it was really wierd because I do not have power steering, then all of a sudden my steering wheel started shaking violently kinda like my wheel was about to just fall off. I pulled over and poped the hood. The trans mount bolt had back out somehow. So i took the car home and put it back in and tightened the nut down. I didn't think that it was the bolt because it had not backed out too much. So today on my way to work it started to do the same thing. It started shaking violently at around 40mph. I thought my car was going to end up in a ditch. I have no clue as to what it can be. When it comes to suspension I do not know much. It started happening after I got two new front tires put on. I do know what unbalanced tires & an out of alignment car feel like and the shaking is nowhere close. Any help would be appreciated.