A troop transport that can't carry troops, a reconnaissance vehicle that's too conspicuous to do reconnaissance, and a quasi-tank that has less armor than a snowblower, but has enough ammo to take out half of D.C.
Though this is a pretty accurate description of Bethesda's APC from Fallout 4, it does raise the question: What would armored vehicles in the Interplay Fallout Verse look like, or be inspired by?
Oh, and to get it out of the way early, I'm not referring to the M4 Sherman style tank, from Fallout Tactics.
Well, we don't know, BUT, based on the fact that Fallout is the Jetsons as envisioned by the 1950s, I'm gonna say hoover.
Maybe not the frontline vehicles, but the armored scouting cars, howitzers, etc, hover and only have rudimentary all-wheel drive capacity for emergency breakdown purposes. This would make almost all-terrain vehicle appropriate, no matter how muddy or rocky or shitty. And if it helps Jules does mention hover capacity and anti-grav plates for the Highwayman after beating the Enclave. Tanks and IFVs if not the same thing, would be based on the same chassis for ease of maintenance and production. Wide tracked for invading the Soviet Union on shitty roads and tracking down partisans in third world conflict, which extensive use of anti grav plates as needed to get the vehicles out of mud or trenches or across weak bridges.
Oh and given the nature of overengineering in the prewar (the crappy water chip lasts 90 years without maintenance remember?) These tanks are SUPER COMPLICATED but rarely break down, but if they do and a retreat is called for, the tanks are torched rather than defended.
Stocks of armored vehicles in the States would be very very VERY low, with exports to Allied European and African countries: they help friendly regimes maintain order and then those regimes give resources to the Americans in kind. Except when Chinese subs sunk them. The Battle of the Atlantic is EVERYWHERE and US Navy is trying to preserve the trade structure that made the Pax Americana possible.
Power armor is used so much because they can maneuver in rough terrain around Chinese formations and power armor is by definition made for crowd control. Tanks are used as blocks while more cost-effective power armor flanks and destroy, with tanks and IFV's being used as pursuit.
EDIT: In short, never forget that military vehicles are designed around doctrine, not the other way around. So to understand what the vehicles might have looked like we need to examine doctrine, which there's no evidence of, and we can only conjecture based on the technology we've actually seen.