Towing with your 4WD; the ultimate guide
Towing is a subject that comes up often and yet remains overlooked by many, and that’s quite scary. It’s extremely important that you understand what is legal, safe and sensible when it comes to hooking something onto the back of your 4WD, and this post dives into everything you need to know. We start off with towing weights, and then move onto mirrors, gearing, brakes, water tank levels, weight distribution, speeds and more.
Whether its a caravan, camper trailer, boat or normal trailer, the consequences of towing incorrectly or illegally can be disastrous and very costly.
There are a huge number of people on the road in Australia today who are driving overloaded vehicles, or towing more than what they are allowed to do. Not only does this void your insurance, but it opens you up to huge fines and most importantly increases the chance of you killing or injuring someone
A lot of people get confused (and rightly so!) when the technical jargon is thrown around, so this is the ultimate, easy to understand towing guide. Please remember that ignorance is not an excuse, so please share this around to those who may find it useful.
We’ll start with the vehicle that you are towing with. From the factory, it comes with a set of limitations; how much weight you can put in it, what weight trailer you can tow and what the total trailer and vehicle weight can be. The first step is to find out what these figures are.
Finding out the figures for your vehicle
Take a quick detour to www.redbook.com.au, and select your make, model and year. Pick your vehicle from the list, and head down to the dimensions section. It’s vital that you pick the right model – manual or automatic, with the right engine as these figures are not the same across all models.
Payload (or maximum weight allowed on your 4WD)
This is the first of a few very critical pieces of information that you need to know. It refers to the maximum amount of weight you can add to your 4WD. This includes everything from passengers to 4WD accessories, food, water, clothes, tools and also the tow ball weight of your trailer. If it adds weight to your vehicle, it comes out of your allowable payload.
Your payload comes from taking the kerb weight (dry weight) of your 4WD away from the GVM (Gross Vehicle Mass, or maximum loaded weight of the 4WD).
Gross Vehicle Mass – GVM (or maximum loaded weight of your 4WD)
The GVM refers to the maximum weight your 4WD can be. It is essentially the empty weight of your 4WD, plus the allowable payload. Remember for towing, that your tow ball weight needs to come out of your GVM.
When you buy a 4WD, it will come with a towing capacity. You cannot exceed this, and there are some sketchy marketing tactics that you need to be aware of. You may not actually be able to tow at the towing capacity marketed.
More to come on that below. Ensure you look at both the braked and unbraked figures, and use the appropriate one. Braked means the trailer has its own brakes; electric, hydraulic or mechanical. If electric, ensure the vehicle has a tow controller fitted.
Maximum tow ball weight
Along with a towing capacity, 4WD’s will come with a maximum tow ball weight. This is the downforce that a trailer applies to the tow ball of your 4WD. Sometimes replacing the tow bar with a quality rear bar can increase the maximum tow ball weight, but you need to consider this.
Towing speed restrictions
Asides from the normal speed restrictions for vehicles towing a trailer, some vehicle manufacturer limit the speed you can drive at when towing over a certain weight. This is the case for Subaru, who say you are restricted to 80km/h when towing.
It’s easy to be overweight even without a trailer
One of the best things you can do with your 4WD is take it to a weighbridge, when its loaded up and ready to travel. However, be prepared for a bit of a shock; most people grossly underestimate how much their vehicle weighs. Let’s look at a quick example, and see how easy it is to be over weight.
A 2010 Toyota Prado automatic with a 3.0 turbo diesel engine has a payload of 615kg. Most 4WD’s range from 550kg – 1050kg.
Now, we add the below weights:
2 x adults (140kg)
2 x children (60kg)
60L of water (65L)
60L fridge with food (70kg)
Rear drawer system with cargo barrier (50kg)
Spare parts, tools and recovery gear (30kg)
Steel bull bar and winch (65kg)
Aluminium full length roof racks (20kg)
Second battery (25kg)
Clothes and personal gear (45kg)
Cooking equipment, tent and chairs (90kg)
Without anything even remotely excessive, your weight is already 660kg, so you are overweight. What about the tow ball weight, rear bar, second tyre, long range fuel tank, solar panels, bigger tyres, scrub bars, sidesteps, work lights, fishing gear, dive gear and extra engine and driveline oil, or the many other items that people take with them?
I’ll quickly mention this, as its just as important. Your vehicle should be loaded evenly. Just because it has a 1000kg payload doesn’t mean you can plonk all 1000kg on the back of it (in the tray, or rear of a wagon).
On top of this, your tyres have maximum load ratings, as do your axles themselves. You might be able to comply with GVM, but if you are over on the axle weight at one end its all null and void.
Your trailer information
Every trailer in Australia should have a nameplate attached to it, which covers a number of important figures.
Tare weight (unloaded weight)
The tare weight of your trailer is the unloaded weight. This is usually without the water tanks being full, and only counts items that are physically bolted to the trailer. However, a word of warning here; many nameplates are not accurate. Only some top quality companies will weigh their trailers as they are sold and put nameplates on them.
You’ll find plenty of people who have been told a tare weight of 800kg only to find out when they weigh it empty its more like 1000kg. Don’t take the tare weight as gospel, as it probably isn’t.
A common example is camper trailers being plated the same regardless of what size tent, or what extra’s are attached. Obviously a 14 foot tent is going to weigh more than a 9 foot one, and if you ask for an extra battery to be fitted your tare weight should increase as a result of this.
Your tare weight is very important to consider, as its a guide as to the minimum work your 4WD will need to do in order to tow the trailer. If it struggles to tow the trailer empty, then its not a suitable vehicle.
ATM – Aggregate Trailer Mass (maximum loaded trailer weight)
The ATM is the maximum amount a loaded trailer can weigh, once you’ve added everything; fuel, water, full gas bottles, clothes, bikes, solar panels and anything else that adds weight. If you take the Tare Weight away from the ATM you essentially get the ‘trailer payload’.
Again, this is very important; if you have a 1500kg tare weight trailer that has an ATM of 1900kg, you can only carry 400kg! If the tare weight for some reason is actually higher than what the nameplate says, you can be in trouble very quickly.
Tow ball weight
The Tow ball weight of your trailer is not normally on the nameplate, as it varies dramatically depending on how you load your trailer. The general guide for Australia is 10% of the loaded trailer’s weight should be on the tow ball (but this is not hard and fast!). If your trailer weighs 1250kg loaded, you should aim to have 125kg on the tow ball.
You can use normal bathroom scales as a guide if its under 100kg, and you spread the weight and do it carefully. Alternatively, all good automotive shops sell trailer tow ball weight scales.
There’s plenty of ways you can adjust your tow ball weight, but you should be aiming to have the majority of weight down low, and near the centre of the axles. Don’t go and bolt a big toolbox on the rear of your trailer to reduce the tow ball weight as you’ll end up with terrible sway issues due to poor weight distribution.
Other critical information
Your trailer should have chains that connect to your 4WD, and they should be shortened to a suitable length, and crossed over when you hook them up so if the hitch does fail the drawbar lands on the chains and gets caught.
Trailer chains should be attached using a proper D shackle, or a Mawby Hook. Normal lifting hooks are not a good idea, and their legality remains questionable. I’ll do a post on this soon.
In a worst case scenario, its possible for your trailer to completely depart from the tow vehicle (like if your tow bar snaps off). In this scenario, its important that you have a working breakaway system. This is generally a cable that attaches to another point on your 4WD, and when stressed it will pull out, and engage the trailer brakes.
These are mandatory for all trailers that weigh over 2 tonnes, and often come with their own battery system to engage the trailer brakes. The intention is simply to make the trailer stop quickly if it breaks away from your vehicle, so it doesn’t plough at speed into anyone or anything!
Every trailer in Australia over 750kg must have brakes. These can be electric, and are controlled by the tow vehicle, or they can be hydraulic or mechanical via a cable. The latter two rely on the hitch to move back and forth and mechanically apply the brakes on the trailer. If it weighs more than 750kg and doesn’t have brakes, its not roadworthy.
If you have a trailer with electric brakes, you need a brake controller to operate them. Most of these are located in your vehicle, and are permanently installed, but there are a few portable brake controller options on the market today.
Regardless of what you have, you need to know how to adjust it, and make it work when it needs to. Ideally you should understand how to manually activate the brake too, so you can straighten sway issues with just the trailer brakes if needed.
If your trailer is wider than your 4WD, you need towing mirrors. There’s no grey area at all; you simply measure the distance through the two front windows to the outer edge of your mirrors, and if the trailer is wider than this at any point, you need towing mirrors.
These are hugely important for seeing what’s going on behind you, checking a tyre hasn’t come off, and nothing is going wrong. There’s nothing worse than getting stuck behind someone without towing mirrors, knowing they are completely oblivious.
There’s a lot that goes into getting the right tyre pressures, and this applies to your 4WD and your trailer. Fortunately, there’s a simple way of calculating the right tyre pressures for bitumen driving, which you can read here – Caravan Tyre Pressure.
If you head off road, you should be lowering your tyre pressures on your 4WD, and on the trailer. Don’t forget the latter, or it will shake itself to bits.
Loading your trailer
As mentioned above, its important that your trailer has good weight distribution. Put light weight items up high and away from the axles of the trailer, and anything heavy should be down as low as possible, and near the axles.
The more weight you have higher and further away from the axles the more pendulum effect you’ll get when towing, and you wouldn’t be the first person to have a van make the 4WD lose control and end up with the whole lot on its roof.
Water tanks; should you travel with them full or empty?
One of the heaviest things you’ll take with you when travelling is water, and generally the water tanks are at the bottom of the trailer, and near the axles. You should get an understanding of what happens to the tow ball weight when you have full, and empty water tanks, and hopefully it doesn’t make a huge difference to the overall weight distribution.
I’ve seen a lot of people saying they don’t fill their water tanks up until they are nearby, and sometimes (unfortunately) this is because the water makes their setup overweight. Full water tanks are best, especially when you can trust the water savings. The extra weight isn’t going to hurt your economy that much, and your trailer will be balanced properly, with plenty of water available should something go wrong.
Tow vehicle gearing; what should you choose?
When you tow half a house behind you, its inevitable that your 4WD is going to work hard. Even if its a light weight hybrid camper like our 2200kg Reconn R2, your 4WD has to work a lot harder than it would if you weren’t towing.
Each vehicle will have its own specifics, but 5th gear in manuals and automatic gearboxes has always traditionally been weaker, and not ideal for towing. If you have an automatic vehicle, like most are today, you need to be very cautious of the automatic transmission temperatures, as they will go sky high when working hard and locked in the wrong gear, or when unlocked.
Stick with the recommendations in your owners manual, and I’d highly recommend an OBD2 reader to monitor the temperatures and goings on of your 4WD!
Fuel economy and speeds; how to save a fortune in fuel
The moment you hook something behind your 4WD, its going to use more fuel. You might not notice much with the lighter trailers, but go to anything over a tonne and your economy is going to suffer.
I’ve done extensive testing at different speeds on different vehicles, and noticed you will save a significant amount of fuel dropping from 100km/h to 90km/h. The difference in engine and transmission temperatures is significant too, which is important with so many vehicles running at their maximums already.
Sitting at 90km/h is a good idea for a number of reasons, but do it sensibly, and allow people to pass without holding them up. This is all part of basic towing etiquette.
Weight distribution hitches
If you want to shift some weight forward, a lot of people are using weight distribution hitches. These are basically a long lever, and move some weight from your rear axles to the front by way of tension. I’ll be brutally honest and say I’ve never liked these for the forces they generate, and if you need them, things are probably not as well set up as they should be.
For us, they can’t be used off road (even over bumps) and that rules them out completely, but there is zero reason why you cannot have a well balanced, level towing setup that is perfectly safe without weight distribution hitches. If fitting them helps, and they suit your use case then there’s no issue with them, but I really question whether they are the right solution; its a band aid at best.
Towing video demonstration
If you’ve never seen dashcam footage of a 4WD towing a van lose control and end up on its side (or roof), you should. Here’s a small demonstration, and then it covers how weight distribution can badly affect your stability.
Hitch height and adjustable hitches
When you are driving down the road, your trailer and vehicle should be level. If your car has its headlights pointing towards the sky, or your trailer drawbar is pointing down towards the road you have a major problem. Yes, you can tow like this but its shocking for stability and safety, and you need to be getting it level.
One of the ways you can do this is by installing a suitable hitch, or one that is adjustable. This might not fix the issue if your suspension is too soft, or you have too much weight in the back of your vehicle (or front of the trailer), or the car is too tall, or too low for the trailer you want to tow, but it can make a big difference.
If you are wondering whether you can flip your tow hitch, we have a post covering this in detail.
Just yesterday I saw someone asking a question about what they should get, do and learn before towing. They’d purchased a brand new, 3 tonne van with a 300 Series Land Cruiser, and were ready to hit the road. Good on them for asking, but they implied that they’d never towed before and this is a recipe for disaster.
There is 100% an element of skill and education required for towing a trailer, and the fact that you can hop in any vehicle and tow a huge caravan around without any prior experience, education or training is nothing short of ludicrous, and more than likely a big contributor to the many accidents that happen each year.
If you are new to towing, do a towing course with a reputable business and get the basics right. There’s a lot more to learn than you might imagine!
Joining the tow vehicle to your trailer
Asides from the trailer chains that we covered above, you need to make sure your brakes are working, the breakaway cable is attached properly, Anderson plugs are in and secure, the hitch is locked in its travel position, the jockey wheel is secured in its upward position (or removed) and nothing is hanging down. If you run a stone stomper this has to be set up too.
When it comes to joining your trailer to the tow vehicle, ensure the following:
Your vehicle’s payload is under the allowable GVM figure, including the tow ball weight
If you put your 4WD on the scales with the tow ball weight applied (as in the trailer off the scales and just the 4 vehicle wheels on it) what does it read? Is it under the GVM rating for your vehicle? Are the axle weights under their maximums?
Your vehicle has a towing capacity that exceeds the loaded weight of your trailer
When you weigh your trailer, is the end result less than the towing capacity of your 4WD? If not, you are in trouble from the get go.
Your trailer weighs less than the ATM (maximum allowable trailer weight) when disconnected from the tow vehicle.
When you weigh your trailer only (all wheels plus the jockey wheel on the ground) does the final result come in under the ATM figure given for your trailer? If not, you’re not legal.
Finally, make sure that your GCM is correct
GCM – Gross Combination Mass (maximum weight of your tow vehicle and trailer combined)
The GCM is another figure you need to adhere to, which is the total weight of your vehicle and trailer combined. Sticking with the above Toyota Prado example, your GCM would be 5490kg. If your Prado weighed 2950kg (just under the maximum GVM), that gives you 2540kg remaining (but the maximum towing capacity is only 2500kg).
Sagging rear springs on the tow vehicle
One of the most common issues seen on tow vehicles is a rear end that sags down. From the factory, 4WD’s are often fitted with softer springs that allow for a comfortable ride when not loaded up. However, if you put a few hundred kg of gear in the rear of the car, and add 200kg of tow ball weight, the springs will sag badly. This is a serious issue, as it badly affects the handling of your vehicle and shines your headlights straight into oncoming traffic.
The correct solution is to fit springs that are rated for your application. A decent suspension shop will help you with this, and ensure that the weight you carry matches the springs. Be aware that if you carry different weights in your 4WD, heavy duty springs will result in a harsher ride when the vehicle is empty, so discuss this with the suspension guys.
A lot of people seem to recommend the fitment of air bags to stop a vehicle from sagging in the rear. My advice is this; be very cautious of fitting air bags. They are essentially heavy duty bags (like what most trucks run) that assist in lifting the vehicle up as you inflate them. However, many people misuse them, and they can cause serious damage.
Air bags are fantastic for vehicles that carry different weights, and that are well loaded and within the manufacturers specs. Too many people install air bags and then think they can add more weight, which results in bent chassis and all sorts of nasty problems.
On coil sprung vehicles the issues is lessened as the airbags put force in the same spot your springs do. On leaf sprung vehicles though (pretty much all Utes), they create a third point where pressure is applied, and it can be a serious issue.
The lesson is simple; fit springs as a first resort that are suited to the weight you are carrying, and air bags if you really need to, for those carrying variable weights and that are under the weight capacity. Ask your manufacturer if they will warrant chassis damage if you have airbags fitted?
Air bags are fantastic, when used sensibly and for the correct application. Unfortunately, this is often not the case, and they get a bad reputation.
Weigh your setup
I mentioned earlier that it is imperative to weigh your setup. There are weighbridges all over Australia. Some are free, some will give you a verbal or visible readout for free and others you have to pay for. The idea is simple; take your 4WD and trailer to the weighbridge, and weight them both together while hooked up.
Then, unhook the trailer and weigh it along, and also your 4WD on its own. Make sure you are under the GVM and GCM.
Does it feel safe?
Even if your setup is within the legal boundaries, does it feel safe? If you find the handling of the vehicle are a bit sketchy, have a think about what the consequences could be. There are some truly devastating caravan and 4WD accidents every year in Australia. Is it really worth the risk?
Think and research before you buy
I read stories all the time of people who’ve gone out and purchased a lovely caravan and beautiful 4WD, only to load them up and be told they are probably overweight. Sure enough, they head to a weigh station and they are over by a mile. Not to the point where you can get rid of a few things from your vehicle and be on your way; to the point that their tow vehicle is not suitable for the van they have purchased.
Unfortunately, information like this is not well known and people lose an absolute fortune buying vehicles that aren’t suited to their purpose. The more research you do before committing your hard earned coin the better off you will be.
4WD’s are not designed for what many use them for
If that seems like a funny statement, bear with me. If you intend on buying a 4WD and extensively modifying it, and then towing a big Caravan (3 tonnes plus), you are not buying the correct vehicle. You are running right at the edge of what they are designed to do, and you will have issues as a result.
With everything getting heavier, its no wonder so many people are cluing on and getting something more suitable for the job. We’ll leave you with this post – Is your 4WD suitable, or do you need a truck?
Hopefully this post has been of use. If we’ve missed anything, or you have any questions, let us know below!