Ok. Let's try to make this as BASIC as possible. How does the vibration sound? Is it high frequency like a heard of pissed off bumble bees? If so, then it's 100% drive train.
Is it low frequency like a flat spot on a tire and you feel it in the seats and steering wheel? THAT is tire and wheel.
Google "Reed Tachometer". If you can find someone with one, borrow it and put it on your dash. If you get a high freq response, drive train. Low freq response, tires. I still have mine. Cost me 900 bucks. I was THAT serious into tore and wheel vibration. I KNOW what I am talkin about here. If you can answer that then we will know what direction to point you.
Answer THAT and we have narrowed it down greatly.