I have the save problem using ct200h 4 yeas old
Replaced tires, balanced wheels , blanced front and ack of te car
Nothing matter
My dealer has no clue and just take te car for day after day with no real result
Any ideas?

 

Ur newer tires should be in the rear.
Put the spare one tire at a time to narrow which tire is the culprit
check your steering pretensioner, should be adjusted from time to time or vibes get to the steering wheel
Increase tire inflation pressure
Worn bushings, ball joints, tierod ends.
Worn u joints or other drive shaft parts.

 

I know this is old, but did you ever find out what the issue was? I'm experiencing the same problem and they can't seem to figure it out.

 

My car vibrates too at high speed LOL its kind of scary as if my wheels might fall off but it could just be road pavement. Dont forget tires have speed ratings from like A-Z or something but Z is like the fastest.

 

I don't know about him but last year I had another problem with vibration. Turned out to be the tires. They were out of round. That sucks.