Tires: Tires?, front end alignment, drive shaft

Question
I just recently had both U-joints replaced on the drive shaft and after picking up the vehicle, I noticed vibration at 65-70mph...it feels like I'm driving on gravel. I noticed the vibration before the work was done but it seems to be more pronounced now. The tires have 46,000 out of 50,000 miles on them...but what throws me also is that the tread on the tires are great...the lowest is 7/32. I've had them balanced and a front end alignment also before the work was done.... Just wondering if I need a new set of tires...Thanks

Answer
John,

Does the vibration feel like it is coming through the steering wheel or the drivers seat?  Once you've noted that, try swapping the tires front to rear.  If that changes where the vibration appears to be coming from, then it is the tires - and most likely irregular wear.  That would indicate a misalignment condition.  

If that is true, get an alignment, then see if the problem diminishes over time.  We're talking several thousand miles.  If so, then you are good to go.

If swapping the tires front to rear does nothing, then the problem is probably not tires and wheels.  It's likely in the vehicle somewhere.