Vibration between 67-72 mph?

Tyres could be the problem, especially if it doesn't make a difference if you're coasting or accelerating.

 

2mac,

Did you have them 'Road Force Balanced' ?
I did that with the tires I got with those FRS wheels,, Mich Primacy HP. I shopped around for a shop that dose this
type of balancing. It measures out of roundness buy forcing a cylindrical drum against the tire.

I had 3 tires fine with 6 lbs of force. One tire measured 21 lbs. Then they balance the wheels conventionally.
They can move the tire around on the rim to see if that makes a difference.
I was told to keep that particular tire on the rear and I "might not feel it".
These were 10 mile old "Take offs" from a dealer,, 17" wheels, 215/45/17 tires.

A tire/wheel can balance fine and look fine but have a 'road force' out of true and you would feel it.
I may just have a bum tire and will have to replace it if I feel a problem like yours...
I'm waiting to add all my goodies at once to my Prius so I haven't tried them yet.

Also Buddy, did you use hub adapter rings with those wheels? A Prius has 54.1mm hub centers.
If the wheels you bought have larger centers, only the lug nuts are centering the wheel on the hub,,,,,
Not the way to do it. The wheel can be tightened down a little off center without them.

 

To know if you need hub center adapters, next time you have a wheel off see if it can be moved up and down on the hub center ring with the lugs off.

If that is a tight fit, you might find a shop that does road force balancing.

But first, see if the bad tire/wheel can be spotted by a buddy in a chase car. If it is obvious which wheel is doing a little dance you could have just that wheel tested for road force balancing.

Good luck!