advantages of alloy wheels on trailers

I'd reckon any advantages would be far outweighed by smashing the trailer wheels on rocks or other immovable objects. Having seen my camper airborne a few times over the years and having to hammer a steel rim a couple of times I'd stick with the steelies.

Isnt it always smarter to have the same rims/tires for car and trailer? Less spares

I agree with Peter on the damage to alloys. + expensive to replace

I'm in the process of ordering a new caravan, and have been told that getting matching alloy wheels for my 100series will save about 8kg per wheel over the steel wheels. Thats 48kg for a tandem axle with 2 spares.

With regards to damaging alloys in any trailer, if you have alloys in your 4by you will damage them first in 90% of cases I would think. To run over something immovable at a speed high enough to damage an alloy, your trailer will be following in your tow vehicles tracks - so you have hit the object with front and rear and trailer wheels!!