Lets hope your new 16.5" wheels doesn't have the low 15 degree bead seat angle the old wheels had back in the '70s as they make a very poor wheel for a trailer.
I tried two different flatdeck trailers that came with 16.5" wheel on 7k axles. Hard side scrubbing as we maneuvered around small loading yards the tires would pop the beads. We tried tubes but side scrubbing on corners caused the tire to pinch the tube and resulted in flats and slow leaks.
Trailer mfg stooped using the 16.5" wheels mostly for that reason.
This from a 4x4 off road website and is typical from others.
"The 16.5 inch wheel had a 15 degree bead angle instead of 5 degrees to make it easier to mount tough light truck tires with a tire machine on a one piece design rim. The problem is the while making it easier to put the tire on these wheels, it allowed it to come off easier too. There is no safety bead design to these rims. The beadlock or Run flat works great at retaining the tire."
"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers
'03 2500 QC Dodge/Cummins HO 3.73 6 speed manual Jacobs Westach
'97 Park Avanue 28' 5er 11200 two slides