I just bought 4 new tires and when i drive on the freeway going about 70-80, my steering wheel shakes like crazy. Does this mean I need to get an alignment ? Or anyone know what the problem is?

Take it back to the tire shop and have them re-balance your tires.

yes, it's most likely that your tires aren't balanced properly.

If that doesn't solve the problem, then go here.
http://www.gsp9700.com/

solves 99% of all vibration. Worked when I got new rims, steering wheel was shaking like crazy, after I took it to a place that had this machine, drives as if it was a brand new car.

That looks like a very very through machine. How much does it cost for each service?

front wheels need to be re-balanced.

Hooman