5 weight facts about your 4WD you might not know

The old weight debacle has been going on for years in Australia, and is still building up steam. Ultimately, you need to ensure that the vehicle you are driving is under its required weights, and the trailer is the same. On a practical level, making this happen is hugely difficult, especially with heavy caravans and 4WD marketing that is frankly misleading at best. 

If you are new to the weights issue, we have a very simple guide that explains the 7 items you need to comply with, and getting them all over the line is a lot harder than you might realise. Here’s the link – Simple Towing Guide.

Now, here’s 5 weight facts you might not know about:

You can be under GVM and still have an overweight vehicle

Your 4WD has a number of weight limitations. One of the most well known ones today is GVM, or Gross Vehicle Mass, which is the maximum your 4WD can weight with all of its gear inside, accessories attached, passengers and your tow ball weight. Still not sure? Check out GVM meaning.

However, its entirely possible to be under your GVM and still have a 4WD that is over weight, and this is where things get interesting. Your GVM is made up of two axle capacities; your front and rear. If you have an excessive amount of weight over one end, your vehicle will be overweight, but possibly still under weight.

For many vehicles towing something heavy, the leverage applied by a big tow ball weight is enough to skew the rear axle capacity so high that it exceeds the manufacturers maximum, and then your 4WD is not legal regardless of whether you meet the GVM or not.

The closer you are to GVM, the more likely it is that one of your axle weights is going to be over, as a lot of manufactures don’t give you much wiggle room when it comes to axle weights totalling the GVM.

Your tow ball weight is looked at in multiple ways

If you put your trailer on a weigh bridge, don’t forget to add the tow ball weight to the trailers total, which needs to come under the ATM. For example, our Reconn R2 only came in at 2100kg or so, and I was quite surprised at that.

However, once you add the tow ball weight the actual trailer weight is more like 2300kg. A lot of people think that just because the weight on the two wheels (or 4) of their trailer is under the ATM they are good to go, and its not the case.

Then, when you are driving down the road you also need to be under GVM, and your tow ball weight is included in this. This is because the trailer is applying the tow ball weight to your vehicle.

Lastly, your tow ball weight is looked at in terms of its compliance on its own. Is it under the maximum your vehicle can take, and that the tow bar can take?

A lot of 4WD’s are over their front axle weight

Front axle weight is an interesting topic that a lot of people who own 4WD’s would rather not consider. From the manufacturers floor, you generally get a small amount of additional weight that can be added to the front axles before being illegal. If you add a steel bull bar and winch, a lot of 4WD’s will be over their front axle capacity with two people in the vehicle.

If you add a secondary battery in the engine bay, a few engine modifications and a set of bash plates, you are almost guaranteed to be over the maximum front axle capacity from the get go, and that’s a rather big problem to have.

Weights change a lot during your travels

When you travel, things get used, moved around, emptied and filled back up again. You also pack things differently, and as a result all of your weight figures will change on a daily basis. Good practice is to weigh your setup when its fully packed, and prior to leaving, but don’t forget about what happens when you start to remove things, or move them around.

When your water tanks are empty, does it increase or decrease your tow ball mass? I’ve seen a number of camper trailers with water tanks behind the rear axles, and an already huge tow ball weight. At the end of your trip, when you are almost out of water, your already huge tow ball weight becomes absolutely massive, and one small dip in the road can be enough to send your into chassis breaking territory.

Some 4WD’s have their own limitations

When you are looking at a new 4WD, make sure that you check out the limitations that it has in place for weights, and towing. Some vehicles for example, are capped at a maximum speed of 80km/h when towing a heavy trailer. 

Likewise, Nissan have a weird reduction in GVM that has to apply when your tow ball weight increases. On the tow bar tongue, it might say if the Tow Ball download is 300kg, you need to remove 410kg from the GVM. That’s 300kg of ball weight, and an extra 110kg just because Nissan says you have to.

Always read your owners manual, and make sure you are aware of any limitations imposed by the OEM.

Running close to the limits is not a nice place to be

The ultimate thing is this; if you are running close to any of the 7 weights, there’s a pretty good chance you will be illegal from time to time, and that’s not a position you want to be in. Keeping things legal is the end goal, and the easiest way to do this is to have a vehicle and trailer combination that suits each other, and is well within their limits.

Our Dmax and Reconn R2 comply with every single weight out there, and although its not by much in some areas we are comfortable knowing that no matter what we do with it, we have some wiggle room to play with. If either the vehicle or the trailer was any heavier though (or the tow ball weight was greater) we’d be in a pickle on a regular basis.

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