I drive the roads in Iraq everyday....as a contractor.
I have been out bymyself and with the army and in our own civilian gun ships.
They will attack tanks with RPGs usually this doesnt do anything but the main gun on the tank is to big to fire usually, with out to much colateral.
To much armor makes you slow and an easy target for IEDs. There comes a point that even the armor on a tank will not stand up to multiple 155 rounds buried in the road. ( I have seen the remains of this vehicle the turret was 100 feet away and the side track armor about the same distance.)
The humvees also get ambushed by guys hidding in buildins or the side of the road. Generally the army just pushes through the area but will some times come by for a second pass.
The problem is that the ambushers will run away as soon as they fire a mag or launch there RPG. So to stop them it comes down to being able to react quickly and put...........time to go