i would also get a wheel balance. BUT if that fails which im thinking it might. you need new tyres. I had the exact same problem, the car would voilently shake on exactley 110km/h. i know exaclty how you feel its very unsettling to have the car shake like that.
just go get a wheel balance, if that doesnt fix it, first replace your front tyres and it should fix your problem, if not try replacing the back also and it should be all smooth. i know its an expensive fix but i racked my brains trying to find the problem and ended up getting 4 new tyres for rego and it was fixed.