I also have 225/75 15's on my 5er.
Just replaced my china bombs with some Maxxis Bravo UE-168 in 235/75 15. They are still a load range D as i had before, but are an LT tire and I lost only 100# per tire, but still are way more than loaded capability of my trailer, so I really didn't lose anything.
Maxxis Bravo UE-168Only other option in a LT 225/75 15 for me was a Pirelli Scorpion, but wasn't paying the crazy price for them.
If you can't go LT on a 15" rim, go with the 8008's again, or buy rims and tires in a 16".