I am planning on Michelin Pilot Sport A/S-3 245/40R19. I will use my 18" rims for winter tires. I am opting for the Pilot Sport A/S-3's over Pilot Super Sport because the A/S-3's are a little less expensive and should wear longer while delivering 90% of the performance qualities of the Super Sport. This car will never see the race track, so the A/S-3's will deliver all the performance qualities that I will ever need. Also, I have a 4 wheel drive truck which I plan on keeping for at least 3 more years, so I may not even use the TLX on a regular basis in the winter for the next few years. I will probably hold off on snow tires until the TLX becomes a dedicated all-year car.
I drove an Audi A4 which had 245/45R18 tires and the Audi seemed much better composed in corners than the TLX AWD with 225/50R18's. I am thinking that the wider tire (lower profile) contributed much to the subtle improvement in handling. The Audi probably also has a more sophisticated front steering geometry, but if the TLX can come close, I am OK as this will be strictly a street car.
A little firmer ride is an OK trade off for a sharper turn in and improved handling.