Welcome to the Forum from NH. Lots of great folks here who willingly share their knowledge, experiences and perspectives.
If you have not already done so, I'd start with the basics:
Are the tires properly balanced. As tires and rims become wider, more care has to go into properly balancing them.
Is the front end alignment in spec?
Are the rims damaged in any way, as even slight damage in the rim's geometry can cause vibrations at speed.
Sometimes, there are defects in tires that can cause vibrations. Sometimes, they can be seen on the wheel balancing machine, but other times, they are not visible.
If you confirmed all of the above as good and within spec, you can try replacing one tire at a time with your spare tire, take it out on the road and see if the vibrations go away. I know that this is labor and time intensive, but if the issue is confined to one rim/tire combination, this may help you isolate the specific rim/tire that is causing the vibrations.
Once you've eliminated the possibility that the vibrations are caused by rim/tire issues, then we can start to pursue other potential problem areas involving the suspension or drivetrain, and there are folks here that are much more knowledgeable than me in those areas.
Other folks will chime in with their thoughts.