I was just thinking nuclear power might be the one thing that makes these beasts mobile and therefore useful. If someone decides that they need to build a nuclear-powered tank and the smallest nuclear reactor available still requires a super-heavy tank, then that would be enough for someone to at least build a prototype super-heavy tank in the 1950's. Given its power and presumptive armor and firepower, it might prove useful in a few operations. Of course, today we know that putting a nuclear reactor inside a tank that is likely to get destroyed is a bad idea, but in the 1950's and 1960's it would be seen as the future of warfare, and the US and USSR would likely build large numbers of them.I'm curious: could superheavy tanks make sense in a nuclear environment? Say, in the mid-50s, when a lot of people still expected that WW3 would include a significant land campaign featuring heavy use of tactical nuclear weapons. In that sort of environment, you want a lot of armor, both to protect against blast and fire and also to provide radiation shielding. You may also want a ginormous cannon so you can fire your own nuclear artillery shells. It would be a complete white elephant, but would this sort of logic be enough to convince the US and/or Russian Army to build a few?
On the other hand the only nuclear-powered tank design in history was the Chrysler TV-8 which wasn't nearly large enough to qualify as a super-heavy tank, so maybe nuclear power plants back then weren't as huge as I thought they were.