Well, first of all, install the Thrustmaster drivers and update the wheel firmware if you bought the wheel a year or later. The old fw in PC has the led on the wheel glowing orange and new fw makes it into green, but that's not the only change.
Then go in tm control panel and set 1080 deg, put all ffb forces to 100%, turn off ffb boost and select autocenter set by the game.
In lfs set wheel turn to 1080, wheel turn compensation to 1.0, ffb strength to 15% for start, ffb steps to 10000, ffb rate to 100Hz. When you move wheel X-axis or other ones by pressing pedals you should see a movement in the right lower part of lfs controler settings. Assign your axis to lfs controls and you're good to go.