I've been reading through all the info I have (which is spotty) and I don't think the TR9 this is what I want, even though it is ZR rated.
According to KBB.com, the two options are described as:
TTX (2) P245/45ZR20 Front & (2) P255/45ZR20 Rear • 300C SRT8
(N/A Base, Touring or 300C)
and
TR9 (4) P245/45ZR20 • 300C SRT8
(N/A Base, Touring or 300C)
I think the difference is that one is designed for 3 seasons (non-winter use) and one for 4 seasons. I think the TTX option is probably the non-winter one...