It is most likely a tire that is out of balance. probably rear tire (mostly felt in floor board and seat) Front tires typically shack at speeds below 45 mph and can be felt in steering wheel
Wheel(s) out-of-balance. Get them checked.
Tires are out of balance
Death Wobble!
The tires may need alignment if it pulls to one side and or the wheels may need to be balanced
There is going to be a make your mark shake it up dance off.
Sounds like a tire out of balance. Have your tires balanced and inspected.
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Your front end is probably out of alignment. Have it checked at a mechanic.
Take it to a repair shop and have them do a block test to determine if you have a blown head gasket.
What make the steering wheel shake is the tires that need wheel balance.
you can ask them a question by going into disneychannel.com and going into shake it up and type down the questions and send.
shake something and it makes a sound