I don't know how similar the TX and the T80 might be, but here are my settings I'm using and I'm quite pleased with them:
I've got the wheel range set at about 60%, wheel sensitivity at about 60%, brake sensitivity up to 75%, feedback strength at 30%, centering spring off, and everything else at default. I did turn on "Track Effects" in the force feedback. The wheel force is surprisingly strong at 30% strength. 40% proved to be too much as my wheel overheated after about an hour and 10 minutes of play and shut down. I don't have that problem at 30%, but I think ~ 35% would be the sweet spot for me, if they offered settings of less than 10% increments.