I'm sure that you find this problem when add the winter mod for GTS:
[Obrazek: 11760069054_8a6b9c3b03_c.jpg]

1:
Look in My Document/German Truck Simulator/mod/ and find the trailer mod.
[Obrazek: 11760063054_55e5b3de75_c.jpg]

2:
After you finded the mod rename it with few "z" in front of original name of mod: like me zzzzzzBena
[Obrazek: 11760391256_90c5ed2e36_c.jpg]

3:
Save it and start German Truck Simulator, and in game the trailer will be normal:
[Obrazek: 11759660565_29d3d128f1_c.jpg]

Enjoy!