I wondered that myself. T class is not always the lowest fare in some markets, even with a short-notice, no advance purchase booking. What is your objective in finding "T" class?
Maybe to get to the bottom of the upgrade line within his/her elite tier......so we can hear a rant about how they weren't upgraded and they always get upgraded lol...only a joke.
I'm guessing the OP is looking for T fares under the assumption that they will be the cheapest fare. A subscription to expert flyer would be the best investment for the OP