As Looshy said, the Pb1 rockets found only on the 190F-8 are the only anti-armor rocket in the game and they do work wonders against tanks. A hit anywhere will usually destory the tank outright. The secret is to hit which isnt all that easy to do. My suggestion is to come in fast (250 TAS+) at a 30-45 degree angle of attack, and put the dot of the reticule right on the target and let loose a volley of 3-4 rockets. If you miss, observe your impact marks and adjust fire. Rockets have just as many variables as dropping bombs.
The British 3in/60lb RP-3 rockets are "SAP", meaning semi-armor piercing. The have the most destructive power of any air to ground rocket in the game and a bit more stout of a projectile as well. They seem to do a bit better vs armor than the US 4.5in and 5in rockets, as well as the Soviet RS-82 and RS-132 rockets which are all straight HE type rockets. You can get kills vs armor, but impact on the less armored areas (top/rear) at the right angle seem to be the norm. More often than not when using HE rockets vs armor you will take out a track, destroy the engine, or destroy the turret.