Replace a Hubcap on a Semi-Trailer

STEP #1: Disconnect the PSI lines.

In this example, we are replacing a hubcap with a PSI system attached to it. So, first, we’ll disconnect the psi lines.

STEP #2: Remove the Old Hubcap.

Remove the bolts around the perimeter of the hubcap, and remove the hubcap.

Let the oil drain into a pan

Remove the PSI insert.

STEP #3: Install the New Hubcap.

Install Hubcap:
With a new seal installed onto the new hubcap, line it up with the bolt holes and install the bolts.

Reinstall PSI:
Thread the Thru Tee for the PSI system and reconnect the lines. 

Also, read Filling a Hub with Oil.