BE SURE YOUR SLIDE-ON IS LEGAL - February 2015
If you're not careful you can exceed vehicle GVM.
Many slide-on camper installations we've seen are illegal, because the loaded rig exceeds the ute manufacturer's rated gross vehicle mass. You need to do your sums before you buy.
When you first check out the payload capacity of cab/chassis vehicles it's hard to see how easily you can exceed manufacturers' gross vehicle mass (GVM) ratings.
Medium-sized cab/chassis 4WDs range from around 1650kg (short cab) to around 2000kg (dual cab) and GVMs range from around 2700kg tp 3000kg.
Large utes (Nissan Patrol, Toyota 70 Series and Land Rover Defender) have tare weights around 2100kg and GVMs of 3200-3500kg.
Slide-on campers weigh typically between 380kg and 750kg, so it might seem that all of them could fit legally on any cab/chassis. That may be so, but it's important to note how ute makers measure tare weight. There are some slight measurement variations, but the maker's weight is usually done with an empty vehicle that has minimal fuel, no extras and no bodywork.
To get a real-world tare weight you need to add: bigger tyres all around and a second spare wheel and tyre (40kg); aluminium tray body (100kg); under-tray tool boxes( 10kg); 'roo bar with a winch (50kg); a second battery (20kg); tow bar (10kg); full water tank (60kg); full long-range fuel tank (140kg); tools (10kg); spare parts (10kg); recovery kit (10kg); full fridge (50kg); food boxes (10kg); clothes (10kg) and two adults and two kids (210kg).
That's a total weight of 740kg that needs to be added to the tare weight, before you can calculate your payload capacity!
It's obvious that your ute may well exceed the maker's GVM if you add the manufacturer's tare weight, the weight of the essentials listed above and the weight of an empty slide-on camper.
Even if your loaded cab/chassis and slide-on doesn't exceed the vehicle maker's GVM there's a chance that the front or rear axle mass limit may be exceeded, because of too much weight on the front or rear axle.
An example is that some utes overload their front axles if a steel winch bar, side rails, winch and second battery are fitted. Others, with short wheelbases, overload their rear axles with only a modest payload in their trays.
That's why slide-on camper weight is critical. As important as minimising weight is the positioning of heavy items, including batteries, fridges, gas bottles and tanks. Ideally these heavy items should be located as far forward as possible, to put that weight ahead of or over the rear axle - not hanging out behind it.
Unfortunately, while there's a legal requirement for camper trailer makers to plate their products with data that includes permissable loaded weights, there's no such requirement for slide-on camper makers.
Check out Trayon Campers' approach to minimising and balancing weight in this video:
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