edatlanta. I'm no tire expert but my guess is that your original tires got warmer because they were maxed out on weight. Or close to it.
When the wife and I were doing the MC thing I made a small cargo trailer to pull behind the MC. It had those 4.80x8" tires on it. Good for about 790lbs at 90 psi. We only had about 300lbs total on the tires so we had a 1200lb cushion. Because of the lightweight we never ran 90psi as it would bounce the little cargo trailer all over the place. We ran 25-30psi. I always rode 5+ over the speed limit and on the freeway cruised all day at 70-75mph. Put 4,000+ miles on those little tires w/o any trouble. Occasionally when we stopped for food or gas I would touch the tires and they were actually cooler than the MC's tires.
IMO tires that are maxed out would seem to be in a more stressed state and that could contribute to a lot of tire issue for people.
Whats interesting is when I was on the Wing forum and trailers and tires came up for discussion, no one cared about maxed tire speed or psi numbers. Then I come on here and it's a different world. Never heard of anyone blowing out a tire on their MC cargo trailers. Maybe a flat or two but that's normal. And everyone was going against all that is mentioned on here about trailer tires.
Didn't mean to get so far off topic, but I was just showing what weight can do to tires.