I don't say you should organize your armored forces like this (depends on the doctrine you use and the roles you want your tanks to fullfit, armored divisions should be used only by those whose doctrine goes along Blitkrieg principles, the rest would have brigades at the most), but it's an example on how to model it.
I'd suspect that armies that don't yet have an "infantry supports armor" doctrine would probably have tank units no larger than battalions or possibly regiments to either assign at the corps level to strengthen attacks or to have as an integral part of the division. As an example, an infantry regiment could include a tank company as part of it's TO&E, or the division could have a tank battalion as part of it's TO&E.