I seem to have a vibration issue when the car is cold. It's a 08 5AT. Around 45-60mph it feels like wheel hop or like the tires have a flat spot. It feels like the whole care is going to rattle apart it's that bad. After a drive a few miles, the vibration will stop. If I keep it locked in a lower gear say...3rd at 60MPH it will help with the issue but it won't completely go away until the car is warmed up. I have Turanza Serenity Plus bridgestones on my car. Any ideas?

 

The UTQG ranges from 500AA - 600AA.
It's a stiff tire. So yea, when cold you will feel that vibration until the tires warm up.

Happens with my Continental DWS.
Get a softer tire next time around or use winter tires during the colder months.

 

Sounds like flat-spotting to me, bump up your tire pressure a little and it should help.