What to Consider Before Purchasing and Towing a Camper Trailer or Caravan
Towing a camper trailer or caravan, everything we believe you need to know.
In this blog post we take you through everything that you need to consider when thinking about purchasing and towing a camper trailer, caravan, or something else that weighs more than 750 kgs. There are a few key points that need to be addressed which we go through in detail to ensure you have considered everything before you make that expensive purchase.
Our Camper TRailer
As most of our readers and followers on social media will be aware, we tow an Australian made off-road camper trailer, DOT 373. DOT being an acronym for Drifta Off-road Trailer and the 373 being the build number. Unfortunately for others, DOTs are no longer in production with 373 being one of the last few made back in 2020.
When we made the decision to purchase our camper trailer a couple of key factors came to play straight away. Being new to the towing scene, other than just a box trailer for jobs around the house and the odd house move, there were a few things we needed to consider before making that big purchase. Here are the key points we considered below hopefully providing you with enough information when considering doing something similar.
Key Points to Consider
Below are the key points to consider when looking at towing a camper trailer or caravan.
- Payload and GVM of your 4WD.
- GCM of your 4WD.
- Towing capacity of your 4WD.
- Tow ball rating.
- GVM of your trailer, camper, or caravan.
- Rated towbar.
- Electronic brake controller.
- Charging battery of your trailer, camper, or caravan.
- Suspension setup including airbags.
Let us consider each of the above in more detail below.
Payload and GVM of your 4WD
This is by far the most important factor in all of this, well combined with GCM and towing capacity which we discuss next.
GVM = Gross Vehicle Mass
GVM is basically the gross vehicle mass of your vehicle. This is the legal maximum weight of your 4WD before any approved engineering upgrades to your 4WDs GVM. Your payload is basically the weight you can add to your vehicle while being within its GVM. The payload is calculated by subtracting the GVM from the vehicles tare or curb weight. Be sure to check how your vehicle manufacturer calculates the tare or curb weight to see what is included in this calculation – sometimes it includes one passenger and a full tank of fuel and sometimes it does not. Understanding your GVM and payload is crucial when it comes to towing.
For example, we drive a 76 (70) Series Toyota Land Cruiser. The GVM for the 76 Series is 3,060 kgs. The curb weight is 2,265 kgs which includes all oils and fuel but no passengers. This is standard out of the box with no accessories. Our payload is therefore 795 kgs. This payload now needs to be able to include anything we have added to our 76 Series Toyota Land Cruiser including passengers, accessories and do not forget the tow ball weight of what is being towed. This final point is something forgotten about by many people when doing their calculations. They look at the rated towing capacity of their vehicle and think they are good to go, without considering their GVM and the tow ball weight that should be factored in here. Also remembering that anything you add to your 4WD is going towards your payload, this is one of the reasons we chose to sell our Jeep Wrangler and replace it with a 76 Series Toyota Land Cruiser. Once we hitch up our trailer, we are basically on our GVM when we add that additional tow ball weight, that is how close it is. We are going to do a couple of modifications in the future that will give us an increase to our GVM to provide a bit more comfort here, but for now we must be careful how we load our 4WD and trailer.
GCM of your 4WD
As highlighted above, this is another significant factor that needs to be considered when towing a camper trailer or caravan. You might have sufficient GVM when including the tow ball weight of what you are towing, but that does not mean you will be within your GCM. GCM stands for the gross combined mass of your 4WD. This means the combined mass of your vehicle and what you are towing.
GCM = Gross Combined Mass
Back to our situation. Our trailer DOT 373 has a GVM of 1,600 kgs. It currently is never loaded to the GVM and sits between 1,300 and 1,400 kgs. But for this calculation example we will use the trailers GVM. The GCM of our Land Cruiser is 6,560 kgs. The difference between the GCM and GVM is 3,500 kgs which is the rated towing capacity of the Land Cruiser if the trailer has brakes fitted. As our trailer only has a GVM of 1,600 kgs, our GCM is 4,660 kgs (GVM of 4WD plus GVM of trailer) which is well within the GCM of 6,560 kgs. Do not forget to check that your 4WD and trailer together are within your GCM to ensure you are towing legally.
Towing Capacity & Tow Ball Rating
The next factor to consider when towing a camper trailer or caravan which has been mentioned above is the rated towing capacity and tow ball weight of your vehicle. We have shown you above how these need to come into your calculations when looking at GVM and GCM.
Towing capacity is extremely important when towing a camper trailer or caravan. Being that you do not want to be towing a 3-tonne caravan with a 4WD that has a towing capacity of 2 tonnes. This does seem to be a simple thing to consider but you would be amazed out how many people do not factor this in. Crazy right! You only need to drive on the highway a few times to see a few examples where it looks like someone is towing a lot more than their vehicle can handle. We have always been of the view that it is far more sensible to have a vehicle with a towing capacity significantly more than what you plan to tow. This is because you have the added comfort knowing that your vehicle will tow comfortably with little issues and your fuel economy should be decent.
Then there is the tow ball rating of your vehicle. This also needs to be factored in to ensure that you are within the limits that your vehicle can handle. This is usually 10% of the towing capacity. The tow ball rating of our Land Cruiser is 350 kgs. So again, you want to ensure that your trailer tow ball weight is within this rating. This is where it is a good idea to buy a tow ball scale. They are cheap to buy and allow you to check that you are legal as well as if you have loaded your trailer correctly. This should never be more than 10% of your trailer weight. On the flip side you do not want this to be lower than say 7% either as this means you have not loaded your trailer correctly. We have a tow ball scale that we purchased from Speedy Towbars and this works well. You basically sit this under your tow coupling (we must sit this under the A-frame of the trailer as we have a DO35 hitch), then jack up your jockey wheel until it is off the ground and check the tow ball scale reading. Our trailer when fully loaded has a tow ball weight between 120 and 140 kgs which is close to 10% of the weight of the trailer (remembering we are not at the trailer’s GVM). So, we are well within the 350 kg rating. Make sure you consider this as some 4WDs will only be rated to 200 kgs. Again, knowing your tow ball weight is imperative as this needs to be factored into your payload calculation that we discussed earlier. So, we need to ensure that we have another 120 to 140 kgs of payload available to stay within our legal GVM.
GVM of your Camper Trailer or Caravan
As discussed above, you need to know the GVM of your camper trailer or caravan when towing. This is the maximum weight the camper trailer or caravan can legally be once fully loaded. Your trailer manufacturer will let you know your tare weight and what this includes or does not include. Again, as per the calculation for your vehicle GVM, the difference between the GVM of your trailer and tare weight is your trailers payload. This is also important to ensure that you do not overload your trailer. Be super careful here as we have heard of some dodgy numbers from trailer manufacturers, and they leave out a lot of things when giving you this figure. So, we would recommend getting your trailer weighed independently at a weigh bridge to make sure you have your calculations correct. This will also ensure you load the trailer correctly, as when you get your tow ball weight you will know if you are around the 10% figure.
For example, DOT 373 has a tare weight of 980 kgs. That does not include any water in the two 80 litres tanks but does include everything else fitted to the trailer. This includes the rooftop tent, battery, electrical, awning, kitchen, fridge and so on. So, once we fill up the two water tanks, we are at 1,140 kgs. Once we add all our other gear and bits and pieces the trailer ends up somewhere between 1,200 to 1,400 kgs. Remember to check what the tare weight of your trailer includes and excludes as you might get a surprise when you take it to the weigh bridge.
Rated Towbar
Now that you have worked out all your weights above and you are within the legal limits of what your vehicle can tow, you need to ensure you have a rated towbar that meets all your weight requirements. We had a Class 4 heavy-duty tow bar supplied and fitted by Speedy Towbars. This tow bar is rated to 3,500 kgs, which is more than adequate for the weights we will be towing. Make sure that you check your tow bar rating as some tow bars will be rated well below the 3,500 kg rating that we have. We would highly recommend speaking with a company like Speedy Towbars who have been in the tow bar industry for 20 years as they know what they are talking about and will ensure that you get the right setup for your towing requirements.
Electronic Brake Controller
If you are towing a camper trailer or caravan that weighs more than 750 kgs in Australia, your camper trailer or caravan must be fitted with electronic brakes. As a result, you will need to ensure you have an electronic brake controller fitted to your vehicle to safely control the brakes on your trailer or caravan. This could be fitted yourself, but we would highly recommend having a tow bar fitter install this to ensure it is done correctly as this is one thing you do not want to fail when out on the open road. There are quite a few different options in the market, but we chose to go with a tried and tested Australian brand, Redarc and fitted their Tow Pro Elite V3 electronic brake controller. Again, we had Speedy Towbars install our Redarc Tow Pro for us when they fitted our tow bar and a few other things to our 76 Series Toyota Land Cruiser. The brake controller is fantastic and makes towing so much easier and safer. You can read about our Redarc Tow Pro here. The trailer brakes are controlled from the Redarc brake control knob that allows you to adjust the sensitivity of the trailer brakes. This is great as you can adjust the settings based on the type of driving, highway or off road, as well as if your trailer weight has changed. For example, we will turn it right down when getting on the beach at Fraser Island and driving through thick sand. We will also turn it down slightly on our way home as we would usually have used up most of the water and a few other things so the trailer weight would have reduced by anywhere up to 200 kgs.
Anderson Plug for Trailer Battery
When you have your electric brake controller and tow bar fitted, make sure you have an anderson plug fitted at the rear so that you can plug in your trailer to charge its battery while driving. Again, we had Speedy Towbars do this for us when they fitted our towbar and brake controller. We had them connect the anderson plug to our second vehicle battery as well to ensure that we have no risk of draining our starter battery.
Suspension Setup
The final thing to consider when towing is your suspension setup. Depending on the tow ball weight of your trailer, having air bags fitted might be a good option. Having that additional weight sitting on your tow ball will put significant pressure on your rear suspension. You do not want to have the rear of your vehicle sitting low and the front raised up. This is unsafe when driving and can lead to several issues. If your vehicle is not sitting level when you hitch up your trailer, we would highly recommend fitting air bags in the rear.
For example, we have a tow ball weight of 120 to 140 kgs as we highlighted above. Our rear springs are rated to 350 kgs, so we have a stiff rear suspension setup for the load we are carrying. If we do not have much else loaded in the rear, then we only see a very small sag in the rear of our 76 Series Toyota Land Cruiser. But when we go off-road and we drop our tyre pressure, the rear sag becomes more noticeable. Especially in the sand as we can be as low as 15 PSI in the rear. Before we had our suspension upgraded with a 2-inch legal lift and air bags, at the beach our Cruiser sat noticeably lower in the rear. This caused all sorts of problems when going through thicker sand and steep drop offs on some of the inland tracks at Fraser Island (we damaged a few things that we could not avoid due to how low the rear of the Cruiser was sitting).
Having air bags makes levelling out your vehicle super easy. When the trailer is not hitched, you measure the height of the rear wheel arches to the centre of your hubs and remember that distance. Then you hitch your trailer, make sure you are on level ground and take that same measurement. You might see that you are now lower by 10 or 20 mm depending on the weight of your trailer and suspension setup. Then it is a matter of adding a bit of air to the air bags and measuring again. Once you get your vehicle back to the correct height, remember what PSI you added to each air bag for next time. It probably will not be the same every time as your weights can vary but it will give you a good starting point.
For example, the distance between the centre of our hubs and the bottom of our wheel arches is 610mm when level. The air bag on the right is always set at 14 PSI and the left 8 PSI. The right has more weight due to the spare wheel sitting on this side. When we hitch the trailer and the trailer is fully loaded, the measurement can go from 610mm to 590mm depending on how much gear we have in the back of the Cruiser and in the trailer. We would then pump up the right air bag to somewhere near 35-40 PSI and the left one to about 25 PSI. This will be a bit of trial and error for your setup. But we would highly recommend fitting a set of air bags to the rear of your vehicle if you are towing.
Additional Information & Resources
If you would like more information on our towbar, Redarc TowPro Elite, suspension setup and everything else relevant to this post, see our blog posts below. This is not a sponsored post. Speedy Towbars have done work on all our 4WDs over the years and have always done a fantastic job, providing amazing service and are a locally owned family business. As a result, we would highly recommend them to anyone else interested in towing and need further advice and information, they know what they are talking about.
For more information on Speedy Towbars click here. For more information on the Redarc Tow Pro Elite electronic brake controller check it out on Speedy Towbars webstore here. If you would like to see the towbar we had installed, check this one out on the Speedy Towbars website.
We hope you have enjoyed this post on towing a camper trailer or caravan and all the things that you need to consider. If you have any questions or feedback, then comment below. To keep up to date on future posts join up to the 4WD Adventurer Community here.
Thanks for reading legends.
Disclaimer: This is not a sponsored post but our own views and opinions. Any mention of companies such as Speedy Towbars is not paid for by the company. Our positive feedback is solely due to our customer experience in dealing with a great local Australian small business.
