Yeah, so my car always vibrates... it's not the wheels, it doesn't need an alignment, and I was pretty sure that it might be the front-to-rear driveshaft.
Anyways, the plot has thickened.

It is far, far worse when it rains. It almost thumps... almost a full second interval between said thumps. It isn't like a horrific thump... but the whole car is shaking a fair bit, I can see the headrest moving, and my hands moving on the wheel. This thumping sensation only happens when its raining quite heavily.
It's not the tires... it's done this on at least 2 different sets of wheels/tires.
I'm afraid guys. I have considered calling in an exorcist.

 

You should turn down the bass and see if it stops

 

Buy a second "rainy daycar" ???????

 

Does the thumping vary with rpm speed when you are in gear? If its related to the driveshafts it would. Do you do a lot of launching/clutch drops? Could be an unballanced flywheel.. I dont know man..

 

I would be looking at the drive shaft mounts or the dough nut bush ( I cant say that in American lol ) but its a rubber bushing on the prop shaft

 

As a rule of thumb a vibration felt in the steering wheel usually has to do with drivetrain or wheels and tires in the front. When the seats shake usually its in the rear. Your feeling it from both from what you said. And wet weather throws another equation into the Mix. Maybe something with the clutches in the center differential. Or the rear drive shaft. I would be looking hard at both those areas.

Good Luck...

 

4x4 or fwd?

 

I've got Quattro... Also, I should mention, it is at its worst at around 120km/h or 73~ mph... I didn't want to go any faster to see if it'd go away.

 

And you are absolutely positive your wheels are ballanced correctly? Maybe one of the weights fell off? They do put them on the insides of the wheels too, so itd be hard to notice.

 

haha thats great