HP LaserJet Enterprise M4555 MFP series - Manual (Page 115)

4. Make sure the stack fits under the tabs on the
guides and does not exceed the load-level
indicators.
5. Adjust the side guides so that they lightly touch
the paper stack but do not bend it.
Load Tray 2 and optional Trays 3, 4, and 5 with standard-size
paper
1. Open the tray.
NOTE: Do not open the tray while it is in
use.
ENWW Load paper trays 95