I would suggest not pulling one tire onto ramps to take off the other same side tire. This overloads the one tire that now carries all of the weight of that side of the trailer, possibly causing damage. Tires are rated for only so much weight, and trailer tires are usually close to the max already...to virtually double the weight isn't a good idea.
Jack up one side, then the other. Don't use the axle tube for jacking.
The poster who commented about tire dealers jacking incorrectly is dead on. My experience has been that most tire dealers have no idea about jacking a trailer.
