-When out of long range rockets, it is possible to get close to it without getting hit. First, use sniper rifle to zoom in on the top of the tank and take out the gunner, if there is one. After he is down, throw a smoke bomb in the direction of the tank. Try to get the smoke bomb in as close to it as possible. While the smoke is in the air, you can run up to the tank without being hit. The smoke will make it difficult for the tank to see you. Get directly next to the tank and plant a C4 next to it. After it is planted, throw another smoke bomb slightly further away from the tank. Make a mad dash for the smoke. If you are fast enough, you will get behind the wall of smoke and can then make your way to safety. Then, detonate the C4.
-If you have C4 with a detonator, run to the tank, crouch, plant the C4, then immediately run away. When you get about 10 feet away, use the detonator to explode the C4.