simple balancing question.
 

I went from an 18'' wheels, to 20'' wheels.

@ 70 mph the steering wheel has little to no vibration...

@ 80 mph the steering wheel has a considerable amount more vibration.

Bumps on the road are fine.. just I "think" the wheels are not balanced properly? or is that how it goes? Its manageable , but if its a simple thing like that, why not get it checked out.

Sounds like a balance issue.

Try finding a place that does road force balancing. Its suppose to give a much better balance.