last night while driving my teg i noticed i have a bad vibration in the front end it only happens at speeds over 40mph my tires are ballenced my axels are not broke and my alinghment is good i jacked up the car to check for worn parts and everthing seems to be tight and i checked my ball joints and there ok i put the car on a lift checked both wheels and no play both sides are tight it feels as if my wheel on the drivers side is going to just fall off and i feel the vibration threw the steering wheel any time i pass 40mph any thing else i should look for or maybe check again because i scared my wheels are going to come off while im driving would a bad steering rack cause something like this or a suspension part? 
you might simply have a seperated tire, take it to a reputable tire shop and have them take it off and put it on the balancer and spin it to see if its seperated or if it is “out of round” meaning the tires tread is not uniformly straight, either of the two will cause vibrations ESPECIALY through the steering wheel like you mentioned. seperations will cause it at lower speeds 1-45 er so and when it vibrates at high speeds 45+ usually indicates that the tires are not balanced. check all four tires cause sometimes a bad tire in the rear can cause a vibration also… ~Andee…