If you said that when you "got the new tires and alignment done, it was slightly improved" - it could only mean that your balancing of tyres need to be attended to.
If at all balancing did little to remedy your vibration - then it could be possible that your wheel is damaged somewhere.
My 300SE used to have terrible vibrations.
We found the fault as follows:
Balancing was worse on Dunlop, and improved on Michellin - changed all 4 to Michellin.
Balancing improved with less vibration on steering wheel, but noticeable at 70 mph upwards.
Changed all 4 tyres, and the balancing/vibration has since stopped.
126 tailed by a 203, 129 leading the pack.