could be many things, you'll need to check it
could be
top mounts worn or loose
wheel bearings collapesd (normally would make a noise tho)
Drive shaft, worn or loose
Tracking may be out
un-even wear on your tyres
springs may not be seated properly
Wheels may be buckled?
Tyres may be agains rotation
wheels may need balenced
it really needs to be checked. I was running with bucked wheels and it shook the steering wheel at anything over 30mph, tried balencing and tracking many times only to finally find out 3 of the 4 were buckled