I've had 4 TTs and the first three had steel wheels. I was always told to torque @ 90-95 ft/lbs and that seemed to work well. I have an old style "needle" type torque wrench but I think that gets it close enough.
My current TT has aluminum wheels which are beautiful. During the initial walk-through I asked the technician (who was very knowledgeable and competent) what torque I should use...he suggested 100-110 ft/lbs. I tried that with my existing torque wrench and at about 100 it really felt like I was starting to over-tighten so I left it at that.
I think what I want to do now is get a ratcheting torque wrench that you can set to your desired limit (say 100) and when it get to that point it "breaks" so you can't over-tighten. Expensive though!
Example: Amazon.com: Professional Grade 1/2" 30-150 Foot-Pound Automatic Adjustable Torque Wrench: Automotive
2010 Flagstaff 829RGSS
Still to go: AK, NL, NT, NU, YT