The back armor of the tank is the easiest weak spot to attack, 2 satchel charges and a sticky grenade should destroy the tank. The biggest weak spot is under the tank, 1 satchel charge will destroy it even when it is at full health. To do this, throw a satchel in the direction the tank is moving, run away (extreme conditioning recommended) and detonate it when it is under the tank. Bingo! I hope this helps!