Out of curiosity, counting latest "eastern" tanks of their respective lines:
I didn't count type 96B, because, well, not sure that we've seen its production form as of yet.
type 99A | 58t(?) |
VT-4 | 53t |
Oplot-M | 51t |
T-90M | 48t |
Note: both Chinese tanks are significantly more voluminous inside: VT-4 is simply long, and it was claimed, that 99As' turret became even roomier. However, the hull of Type 99A is substantially rearranged inside, making such a crude comparison even less indicative of what's going on.
Russian and especially Ukrainian tanks squeeze very heavy side protection into their weight. Finally, Oplot is very heavily reliant on ERA.
Curiously, the Russian tank gets to the exact same weight as Japanese type 10 in its full configuration(which is probably the least voluminous modern western MBT in existence).