Thanks all for the responses. Just to clarify:
I do have 205/75/14 and currently Maxxis, load C. The rims are aluminum. The trailer is quite light (about 4000 loaded) so the current tires work fine in that regard.
The main reason I am looking to upgrade is because I now have a grand-daughter who lives in Denver and we live in Vancouver (B.C.) and drive down there quite often, I was looking for a tire that has a higher speed rating as I currently limit myself to about 63 (65 max. rating). Would like to cruise at around 70 with a bit of safety headroom. Not really comfortable running at the 65 max for 8-10 hrs a day for multiple days, repeatedly through the years..
When I enquired about the GY Endurance, the tire guy made a comment about the psi rating of the rims, so I started doing some research and found others had similar questions. And a couple guys did find a max psi stamped on the inside of the rim which posed a potential conflict with their desire to upgrade (their rim was rated at 80 psi and they wished to run a 110 psi tire, if I recall correctly). I can only assume that if a rim has a max psi stamp, then the manufacturer believed psi would have some impact.
I haven't checked my rims (not near trailer right now), but I am comfortable running the GY's on them with a difference of only 15 psi. Was just curious about the rim stamped psi.
Anyway, thanks again for the replies.
Marv