Here's an interesting one. We've got a 28' enclosed trailer that we use for car hauling. Dual axles on leaf springs with a little balancer in between, usually loaded with about 5000 lbs of vehicles. Picked it up new in 2011 and it's done somewhere between 15,000 and 20,000 miles. It doesn't do much tight maneuvering other than at gas stations, it spends the bulk of its time on the interstate.
The tires are showing signs of toe out. The rears are more worn than the fronts overall, which look quite good other than the toe. I keep a close eye on the bearings and pressures, and they always have a cover on them when not in use. It tows very nicely (stable in a 45 mph side wind, as proven on Tuesday) and I always load it with the heavier car up front if applicable. It sits level when loaded (airbags on the truck) and of course they're 225 trailer tires.
I'm going to have to replace all four tires because, well, I hate flats. Is this normal tire wear for a dual axle trailer, or is something else going on?
I have some pretty odd wear on my trailer as well on the two older tires (the other two are new). But mine looks like serious inside edge camber wear, even though I've checked the trailer's camber with it loaded. I thought it was from low air pressure from the P/O, but the outsides aren't worn the same way.
The moral: trailer tires are weird 
Get an alignment. There's a truck/heavy duty shop local to me here that aligns a bunch of the RV's coming up from the Indiana factories. He said most of them are out of spec when they are new. The dealers get them done before they sell them. They heat/bend the axle tubes I think. I had him do an older trailer of mine that was wearing the tires similarly to yours it sounds like. No more funny wear after that.
Honestly, I've given up on trailer tires. LT truck tires from here on out.
Other than that, I have nothing to add besides 30,000kms does not seem an unreasonable lifespan.
Trailer tires are weird for sure, so are the axles. It may well be towed out. You might want to check the alignment. If it's out, a frame shop should be able to tweak the axle for you. I've had one tweaked before that needed a S bend to align. The rears must be the axle that's scuffing on the turns. All of my tandem axle trailers have scuffed the rear axle, not sure why. Rotating the tires will alleviate that.
Another issue might be the pre-stress on the axle. A lot of trailer axles are arched up in the center, so that when they are loaded, they are straight. If you axles aren't pre-stressed or are overloaded, they might end up arched down which will make the tires run on the inside edges.
Strange wear patterns on ST tires is why I switched my enclosed to radial LT tires. They aged out long before they wore out.
Yup you need to heat straighten the axle tubes but be forward if you get it straight it may wonder some in the wind.
Maxxis trailer tires seem to have the best rep on line.
I'm in the market for 5 of them myself as I had a rash of blow out last year. I've given thought about LT's but for the ones everyone likes I need 5 new rims as there in 16's only
Rear axles tend to stretch from turns, create toe out, peel tires. Opinion.
If you got 15k out of a set of tires I wouldn't change a thing except to rotate front to rear every year when you pack bearings and every other rotation have the tires dismounted and flipped on the rims.
Also might want to pick up a $30 hubodometer off evilbay to more accurately track trailer mileage.
It is going in for an alignment tomorrow. We'll see what they say. Now that I'm more aware of this, I'm going to start monitoring the inner edges more. I can figure out the exact mileage on this trailer pretty easily, it only goes on big trips so I just have to add them up.
Any idea why the rears wore faster than the fronts? Not the toe problem, but over the entire tread? They look as if they've gone about twice as far as the fronts have. The toe damage looks to be the same on both pairs.
Rears almost always wear faster, in my experience. I suspect since the center of mass for a stable trailer is always ahead of the center of the axles the front axle just always scrubs less.
