RE: http://tech.military.com/equipment/view/88655/mattax.html?eq_id=88655

Used to use these things to break the bead on 2 1/2 ton truck tires. Swing it and hit the tire right were it seals up against the rim. Used to really jar the old hands when I'd miss and hit the rim.

I never saw this individually issued; it was always part of the 'pioneer kit' that went with every vehicle: the mattax, a wood axe, and a shovel, all locked in a frame that hooked under the back bumper of the hummvee. For everything else, there's the trusty ol' e-tool.