The concept of wheel balancing works on balancing the rubber over metal rim.
Proper wheel balancing means that weight /force is distributed evenly over the circumference of wheel.
IAny error in that will be counter balanced by applying weight inside or outer side of rim as needed.
What if the rim iteelf is not perfectly balsnced even being straight?
As we know that balancing error can to be corrected to certain extent. If too much error then its better to replace the rubber or rim itself.
And error due to rim are seldom corrected and create issues at higher speeds.
I faced similar situation when i bought newfancy voxxen rims for corolla alongwith new tyres.
It was perfect within city but as soon as i drove it on motorway it was horrible.
Tried many places for balancing but didnt help, had to revert back to old rims and issue disappeared completely.
Itry swapping with wheels from any friends car to rule out rim tyre axle issue.