Increasing camper trailer ATM?

I've done it, John, on my Kimberley Karavan in NSW. Many members of our Karavan owners club have done it also, in different states. Though the rules are national, each state applies them differently. Additionally, within states those rules appear to be inconsistently applied depending on the engineer you use to certify the upgrade.

NSW, as always, has the most stringent requirements and the most expensive process.

Bearing ratings and axle size are only parts of the deal. The engineer will probably (should?) consider chassis construction and suspension mounts, spring ratings and tyre and rim ratings and coupling.

You will need to ensure your GTM is upgraded as part of the certification process - that is arguably more important than ATM as all the trailer rules are based on GTM, including the breakaway brake requirement. GTM is the maximum weight the wheels are allowed to carry and is the one most easily checked at a roadside check point.

Trailer regulations are national, specified in VSB 1.
The requirement for breakaway brakes is a national regulation, not state-based and applies to trailers with a GTM (not ATM) above 2000kg.

You may find this PDF document of interest. After much research, I prepared it for our club.



Cheers

Try the manufacturer, my camper manufacturer did mine.

A couple of things:

1.. the rating of an axle is limited to the rating of its weakest link. If you only have 2-tonne bearings the axle is limited to 2 tonnes no matter how big the cross-section of the metal.

2.. The requirements for a breakaway controller is based on GTM, not ATM