Ok so heres the deal. Alot of people is asking about how you can find out the tanks weak spot in bf3. And theres a number of questions to that one. First of all, the back of the tank is always the best place to fire your rpg. On the sides, go for the tracks. and of you are in the front, go for the turret or on top of the tank. Easy as that! Second, the rockets gain power first at some distance. So if you wanna hit the tank with full power, dont be too close. This is for infantry, so if you are a tanker, watch below.
If you are a tanker, this is how to do it: