Rims are easy,
http://www.southwestwheel.com good prices and they ship everywhere. Or you can drive over to Dallas and pick them up. They have about anything you might need for trailering look around and try and beat their prices, I gave up.
You can get all kinds or argument about tires, it's been well hashed out on here. Some folks have no problems with chinese tires and some do. It's kinda like roll the dice.
My thoughts are the biggest enemy of tires is heat. Usually caused by underinflation. That can be caused by neglect or picking up a nail. On a vehicle you notice it usually before the tire is trashed. Not so on a trailer. Just too far away, by the time you realize you have a problem it's usually too late, for both of the tires on that side. The one that broke apart and the one that was carrying all the load and overheated damaging it.
After looking closely at the situation I installed a tire pressure monitoring system. It cost $200, about the same as one tire. When I get ready to leave I turn it on and in a few minutes I know what the pressure and temperature is in all 4 tires. Mine has the chinese tires but they are 10 ply rated at 3500+ lbs. I run 80 lbs of pressure. At 70 lbs the alarm goes off. It also has an alarm for overpressure and temperature, all programmable.
If a tire throws the tread not much you can do but I think most ruined/flat tires are caused by picking up a nail or poor maintenance and not finding out about it until it's too late. The TPMS just lets me roll down the road a little more relaxed.