Recreational & Family - Tire pops on 16" bike trailer

I have a InStep Sierra Double Bicycle Trailer that uses 16" tires, and I have gone through 3 inner tubes in the past week, they keep popping randomly. It's never when I'm using the trailer, just when it is sitting. At first I thought it was too much air pressure and sitting in the heat caused the air to expand and pop. But then I started pumping it up with less pressure and it just pops while stationary. It says no more than 35psi and I'm not going higher than that but it will pop an hour or two after pumping it up. Any ideas what would cause the tire to pop randomly? I can't find any debris in the rim. Should I use less pressure? Thanks in advance!

Hi,
If the tube is popping with a bang, you are probably pinching the tube between the tyre and the rim.
When you get the tyre installed go around and squeeze the sides, you shouldn't be able to see any of the tube underneath.
If there is no bang, there maybe something small in the tyre still, or the rim tape isn't covering all the spokes properly.

What do the holes look like? Are they on the inside or outside of the tube?

As sk0tt mentions, The rim tape is a good suspect.

If the tire bead is repeatedly lifting off the rim and causing a slit in the side of the tube, you may have deformed the tire bead the first time it popped. It took two tries on one bike in a bike shop where I once worked to learn to always carefully inspect the bead on the tire before replacing the tube if it suddenly popped on the bike owner. If the bead is deformed, the lifting will always occur at the same location on the tire. You can match up the valve and valve hole and the location of the hole on the tube to figure out where to look on the tire. Replace the tire if it is not caused by something else on the rim.