Hmmm, valid point... But mobility is still to interstate or hwy travel due to the brads weight, can't see a brad crossing a bridge on a county or municipal road. Plus they ear splitting loud on the inside, might we compromise with a LAV or Stryker?
32 tons (34ton combat weight) is less than that of your average loaded out semi. Much less the super heavies you see on the interstate. You average semi is 80,000 pounds so just about 40 tons. Add in the fact that any super small bridge that can't take the weight can always be by passed by just going through the culvert.
A Stryker? The fuck you will ever get me inside one of those, they are open topped in the rear, lightly armored and are of the shit tier for cross country mobility and reliability. I would say if you think the brad is too heavy or not mobile enough then a simple M113 Gavin would be the best for you then. They are fast, easy to maneuver, still armored relatively well, and being tracked have the benefit for being able to run over the entire zombie hoard. Wheeled vehicles are just not the way to go with zombie hoards. The ability to not have to fire and to use the vehicle as a weapon is invaluable as ammo will be short so and so will fuel so you need a diesel engine, due to the ability of them to run on pretty much anything.
Honestly though a zombie apocalypse would never happen to the U.S. to many armed and angry people. China? India? Yeah, can we say giant zombie hoards? But in america? The land with more fire arms than people? No. We also have the worlds best trained and best equipped military so they would mow through any hoard in seconds... I can see it now....
"O no our next door neighbors the Sulivans have turned into zombies!" says Mrs. White, "Fucking hated that ass hole anyways, he never returned my cordless drill I let me borrow!" say Mr. White as he lock and loads a 30 round magazine into his AR-15..... See the whole "O no I can't shoot him as I used to know him thing" doesn't really work here in America. More people would die from the panic of zombies even existing and from old grudges being settled them from actual zombie out breaks... Hell I can think of more than a few people I would go and get rid of under the pretense of "zombie infestation"....