Tires: Tires, rear tires, center hole

Question
HI, My husband purchased 4 almost new tires, from a friend for our 04 Ford Explorer. He took it to a mechanic and had the tires balanced, because the car would shake when we got on the highway. Since then it still shakes on the highway and has a overall rough ride. The original tires were 15's and the new ones are 17's. Is this the tires or the alignment?

Answer
Brandie,

It's not the alignment.  

Let's do a little diagnostic work.

Does the vibration feel like it is in the seat or in the steering wheel?  If both, then we can't sort this out.  But if it is only one of those, rotate the tires front to rear and the vibration ought to change to the other location.  If it doesn't then it is not the tires.  If it does, then if the vibration is coing from the rear, it's one of the rear tires.  If the vibration is coming from one of the front tires (or both), then you'll feel it in the steering wheel.

BTW, are the rims aftermarket rims - and if so, did you get a set of hubrings?  The original rims were centered by the center hole and that assures the rim (and tire) are centered on the hub.  Aftermarket rims are not centered by the center hole and can be mounted off center.  That will cause a vibration that changes every time you mount the rim back on the vehicle (because it is in a different location).     

And without the hubrings, you will never fix the vibration.