what would cause for a viabration in my frount end when i am on the highway i know its not the tires cause there new and balanced. what else could it be

There may be a problem with the tires because they're not round or they don't roll round or they have belts that aren't correct. The balancing may not be correct.

Go back to the dealer and tell them there'* a problem that wasn't there before the new tires.