The A400 and the C-17 are big enough for these vehicles, the C-130 isn't. The C-17 can also load a Main Battle Tank. The A400 is to small for that, even if current A400 problems are resolved.
Can I ask why you would need to move a MBT by air?
Even if you could and wanted to, the logistics chain behind a MBT is massive and therefore it is uneconomical to move it this way as such. There are also plenty of papers out there which say the MBT in its role as an MBT is dead...
I am involved in a programme where I am trying to inform land guys why you can't really move a 30T AFV by air even though they have plucked the 30T figure from the air...find out what the vehicle needs to do, "design it" and see how much it weighs then work towards that, not start with a weight and go from there...
Regards