Croozer bike trailer optimalisation for less tire detoriation

400 km on asphalt seems ridiculously low on any bicycle tire.

Try some tough and very durable touring/commuter tires, like the Schwalbe Marathon line. On a bicycle, you should be getting well over 10k miles on those, though due to the smaller wheels on a trailer, you will likely get something less (a friend of mine who uses a recumbent trike gets approximately 2.5k miles on a set).

Also, try to ride smoothly - if for example you're skidding the wheels, then you'll also wear the tires out unnecessarily. It would also be good if you posted how the tires were getting worn down.

My first suspicion would be the alignment on the wheels, if they are not properly aligned then they will wear, but I'm not certain what you can do to adjust the alignment on that trailer. Check the dish of the rims and also make sure that they are true, this may affect how the alignment and how the wheels roll and wear.

If the tires are only wearing on the insides, then rotating them is definitely an option. Swap the tire around on the rims so that the unworn side is on the inside, this may affect how the tires grip the road if they are directional, but you might lengthen their life a bit longer by evenly wearing out the tire.

Often the tires included with the trailers are low quality and will wear quite quickly especially with heavier loads (personal experience). If you simply bought the same tires as the manufacturer included with your trailer as the replacements your problem will persist.

As an alternative, you may want to consider determining the tire size (should be printed on the side of the tire) and purchasing some higher quality tires from a manufacture known for reasonably good quality tires. For example, Schwalbe sell a variety of tire sizes for their big apple tire which wears reasonably well.

That is not scrub a bit - that is scrub a lot. I don't agree a softer tire will not scrub. Yes a softer tire will give bit but then it has no option but to scrub. With no load I suspect the wheels are not aligned perfectly and then those short short axles play. A little play on that short radius is a lot of alignment.

I get you like the portability of the short axles but for long trips go with a trailer with a solid single axle.

This diagram is the trailer being pull toward this line of text. When you brake it is like pushing the trailer and the play would go opposite.

This play is exaggerated but the purpose is to show how much play affects alignment.

In addition to the alignment of the wheels, one needs to consider the alignment of the tongue. The pivot point where the tongue attaches to the bike should be exactly along the centerline of the trailer (even if the tongue is not attached to the center of the trailer), not off to one side. If the tongue (at the pivot point) is not centered then you are dragging the trailer sideways.

My VidaXL yellow/black soft bag trailer wore the tyres due to parachuting effect caused by the empty compartment and top cover letting wind inside. Also the axle retainers were wrong way round promoting too much toe out, I flipped them over and there is some toe-in, that decrease when pulled along. I now leave top cover off empty trailer so wind doesn't drag it down, top cover is placed on floor and used when it is full of cargo. It is also imperitive to angle the hitch downward so the trailer is level or front low which is better, a trailer that planes like a boat also put undue load on tyres. The towing bike is 20x4 fat bike