Drum brake weights interfering with cragar ss wheels

Can someone explain specifically why weights were put on the drums?... I mean I figure it is for balancing but the weight would have to be mounted before the wheels so does that mean the weight is just to balance the brake drum itself?...
I have a vibration over 45mph that I am trying to eliminate. Pulled the rear passenger wheel and looks like there is a weight attached to the brake drum.
Tempted to pull the weight off but like to get some input from someone who knows more than me (that would include just about anyone -lol).