Tires vary, and I don't think there is any real world logic. My last trailer had factory China Bombs for 6 years when I noticed dry rot and decided to change them. We had the camper 2 more years and those Carliles still looked very good.
Our current trailer had factory installed tires and in the 2nd year, one tire showed signs of uneven tread wear and the other 3 were just fine. I swapped all 4 out again for Carliles and it's now been about 3 more years and the tires still look good.
I think the longevity of the tire depends upon a lot of factors.
First, dry rot. If the trailer sits, especially exposed tires to the sun, they run the risk of dry rot. But I've had car tires dry rot sitting in a garage too. If your camper sits in the sun, keep wheel covers over them. This helps against damaging UV rays.
Second, sideways skids. Unless your trailer is a single axle, your tires are going to experience sideway skid every time you make a turn. The primary pivot point may be the front tire, or the back tire and it could be opposite on the other side of the trailer. The sharper the turn (the sharper the back-up turn into a campsite, driveway, or storage) the greater sideways stress there is on the tires. It just happens. Depending on how often, and how sharp your turns will also assist in tire breakdown. Of course, more and sharper turns, the faster the breakdown. But, combined with dry rot by sitting, which is more damaging to a tire?
Third, over-under inflation. Nothing will destroy tire tread and side wall strength than over or under inflated tires. Actually, under inflation is very damaging to the structure of the tire and can also cause excessive uneven tire tread wear. Over inflation can cause uneven tread wear, but also a higher risk of blow out due to excessive heat build up. It's a fine balance to keep the tire pressure in range of the manufacturers recommendations.
Fourth, assuming 1-3 (above) are all well, then you simply have the normal wear and tear on the tread. How long will a tire roll if not under any stress? Well, a long, long time? But now, add brakes to the tire and you've got the possibility of one break being more aggressive and grabbing than the other 3. This could cause one tire to show signs of wear much faster than the other 3.
Fifth? Where do you travel with your camper? If you drive paved roads exclusively, the chances of your tires holding up for longevity are going to be much better than if you drive course gravel roads, or roads with horrible pot-holes, or off-road.
Basically, there really is no way to predict how well a tire is going to hold up. There's just too many factors. I do think some tires are a better build than others, but that does not mean the better build will last longer than the inferior China Bomb if any of the above factors grossly affect, even a very high quality tire. One nail in a tire, high end or low end tire, and the tire's life is pretty much over anyway.
So, the best you can do is simply keep atune to your tires. Never neglect them. Actually, take photos of your tires over time so you can see the progression of wear and tear, and dry rot, and tread wear. If you begin to see cracks on the side walls of the tires, then change them.
Actually, dry rot will happen be the reason for new tires far more than wear and tear on the tire. And dry rot is a hard thing to prevent. A tire sitting long term is probably more damaging than driving that same tire over a gravel road.
Keep on eye on them, and be prepared financially at any time, to replace them on a moment's notice. That's your best prevention.
