Where should you put the iron trailer supports before driving away when you have coupled with a semitrailer?

A Fully raised with the crank handle secured in its bracket.

explanation

Step 15: Raise Front Trailer Supports - Raise the landing gear all the way up. (Never drive with landing gear only part way up, it may catch on railroad tracks or other things.) After raising the landing gear, secure the crank handle safely. [California Commercial Driver Handbook]