Vibration from 50~58 MPH, Help!

Alright guys, so I have an '08 5door automatic, and recently it has developed a bad shake/vibration when going from 50-58 MPH approximately. It doesnt matter whether I am accelerating or decelerating, powered or unpowered. It also doesn't matter what gear I am in, 4th or 5th it doesnt care. As soon as it passes the 58-60 MPH mark it stops shaking, and the same when it goes below 50. Just like clockwork. I just had new tires put on the front less than about 5k miles or so. I am wondering if they didnt potentially screw something up because it started just around the time I got them one. Could it be that my alignment or wheel balance is off? or could it be more like the axle/transmission itself?

Go back to the place you got the new tire installed and ask them to check the wheel balance again. If the wheels are balanced, but you still feel the shake, the wheel itself may be out-of-round (i.e. bent). Or another possibility is that wheel did not get attached to the hub cleanly. If there were too much rust or other foreign material between your wheel and the hub, that could introduce a slight wobble and cause the vibration.

Finally, if none of the above is the reason, check your suspension.