The ‘Oops moment relates to the machinations we had over WEIGHT – the most important consideration of all, but one we came to a tad late.
In all our initial decision making for this wonderful adventure, one piece of fiction led to a number of not so smart decision. The fiction is that if your vehicle is rated as able to tow 3.5t, then that is what you can tow. The fiction, spruiked by so many caravan sales people, is that weight is not such a big issue – “your vehicle can tow this van, no problems“.
Like so many people before us, and many more following us as we read the various forums, we made a quick decision to buy a caravan prior to any serious research, and then we selected a car to tow it. At a major 4WD/caravan show, we signed up for a caravan with a tare weight around 2.75t. We even extended it to include a pantry, adding another 15 inches and 130kg or so, nudging the tare towards 2.9t.
But we had begun to suspect that there was a lot more to this weight issue than we had thought. So we did more research and a lot of calculations and the reality began to sink in. ‘Oops!
There are 2 legal limits that govern all weight considerations for a towing car:
GVM > Gross Vehicle Mass: a legal limit provided by vehicle manufacturers which is the the maximum permissible laden mass of the vehicle including occupants, fuel, payload and the weight applied to the towball.
TBM > Tow Ball Mass: a legal limit provided by vehicle manufacturers which is the maximum permissible weight on the towball with the caravan connected to the towing vehicle
For a Land Cruiser 200, even though it has a 3.5t rated towering capacity, it has a GVM of 3.35t. The kerb weight of a LC GXL is 2.74t, (including a full fuel tank). This means that the maximum load that can be added to the vehicle is 610kg. Sounds a lot, but just only a few items items eat up all of this: 2 passengers at 137kg, alloy bull bar 35kg, car fridge 35kg, roof bars and cage 35kg, and a tow ball weight of 320kg (assuming approx. 10% of van weight) – that’s 562kg. Ouch! But if we take out the rear seats that saves us 35kg, but we will need, a tool box, a compressor, a recovery kit, etc etc, and a slab of beer!
Now bringing the caravan into this equation, there are 3 legal limits that govern all weight considerations for a van and the combined car and van:
ATM > Aggregate Trailer Mass: a legal limit provided by the van manufacturer which is the maximum permissible laden weight of the caravan when it is not connected to a towing vehicle.
GTM > Gross Trailer Mass: a legal limit provided by the van manufacturer which is the maximum permissible weight of the caravan, including payload, when being towed.
GCM > Gross Combined Mass: a legal limit provided by towing vehicle manufacturers which is the maximum permissible laden mass of the towing vehicle and caravan combined.
The caravan we had placed on order had a tare weight of nearly 2.9t when we extended it and added the pantry area. As there would be little payload capacity left in The Cruiser, we had to assume all of our stuff would be in the van. Assuming a payload of 500kg, which requires very careful selection of gear (and rejection), gives a van weight of 3.4t, just under the ATM of 3.462t. The combined mass would be 6.422t, under the GCM of 6.85t.
The overall results of this analysis were:
- a car with a small payload in it and still almost at the GVM, but also still needing some essential other gear
- a van well laden and requiring very careful packing to keep below the ATM
- and more importantly a van 12% heavier than the car, when good practice suggests that the van should be only 70% to 80% of the car weight.
Clearly something had to give, so we had to make changes. We cancelled the pantry extensions for the van, and did a Lovells suspension upgrade on The Cruiser to increase the GVM to 3.8t. We redid the calculations and ended up with everything better balanced and well within legal limits. The only downside being that the van would be about 90% of car weight.
The numbers are shown here
If only we had done the research before we started buying things!