Towing a Caravan or Trailer with Your 4x4: Key Considerations for the Tow Ball weight

Martin Jooste
6 hours ago
5 min read

When it comes to towing a caravan or trailer, one of the most important things to keep in mind is tow ball weight, (also known as tow hitch weight) This is a critical factor that affects the safety, handling, and performance of your 4x4 vehicle.

So, let us dive in and get a better understanding on the subject.

What is Tow Ball Weight on how does it work?

Tow Ball Weight: Simply put, this is the downward force that your trailer exerts on the tow ball and tow bar of your vehicle. It’s usually measured in kilograms (kg) and managing it is essential for safe towing. See the below sketch:

This downward pressure caused by the trailer on the tow ball of the vehicle causes a downward lever action through the weight on the tow ball/tow bar and the distance from the rear axle of the vehicle. This causes the rear of the vehicle to go down and the front to be lifted up. In effect transferring weight from the front axle to the rear axle and increasing the load on the rear axle.

How to calculate Tow Ball Weight?

A = the distance between the centre of the wheels or axles of the vehicle. (In meters)

B = the overhang of the tow bar or the distance between the rear axle and the tow bal. (In meters

X = is the downward pressure of the weight from the trailer on the tow ball. (In kg) How do you measure this? You can get this figure by putting a scale under the towbar hitch of your trailer.

Thus: B divided by A multiplied by X = ?? kg

Let us assume that the weight from the trailer, X is 180 kg

Tow ball weight = 1.2m/2.9m x 180kg = 74.48Kg This is the additional leverage exerted by the trailer on the back of the vehicle.

This means that an additional weight of 180kg PLUS 74 kg = 254kg is added to the rear axle. This figure must be checked against the allowable weight that can be added to the rear axle according the vehicle manual

Why Does It Matter?

There are several reasons why this matter and why it is very important.

Prevent overloading: Each vehicle has a maximum allowable rear axle loading. (Check your vehicle manual) You need to stay within this limit, otherwise you stand the risk of overloading the rear axle and you my damage rear axle components – like wheel bearings. You do not want to do that. You can ask me! You can also overload your towbar and cause damage to your towbar, especially the connection points between the tow bar and the arms connected to the vehicle chassis. Again, you can ask me! (I had a situation where the towbar was torn from the plates/arms that connect it to the chassis because of too much weight on the tow ball. *Luckily this happened at about 10km/h)
Safety: To exceed any vehicle limitations is an unsafe practice. Period.
Handling: A balanced load on both the vehicle and trailer makes it easier to steer and control your vehicle, especially during turns and bumps
Braking: Proper weight ensures that both your vehicle and trailer brake effectively when you need to stop.

What’s the Ideal Tow Ball Weight?

General Rule of Thumb: There is a general rule of about 7-15% of your trailer’s total weight, that is including the load. So, if your trailer weighs 1,500 kg, you’ll want a tow ball weight between 105 kg and 225 kg.
BUT, Check the Specs: Always check the recommendations from your vehicle and trailer manufacturers to stay within the specifications. And do the calculations.

How to Measure Tow Ball Weight?

Using a Scale: As mentioned before, you can use a scale or load cell to check the weight. There are a variety of tow ball scales that you can use. Just make sure your trailer is level when you do it to get an accurate reading.

How to adjust Tow Ball Weight?

Load Distribution: This is very important. It is not just about randomly distributing the weight on the trailer to get the tow ball weight right. It is all about how to balance the weight on your trailer. The following points should be considered during the loading of the trailer. This is not only for camp trailers.
1. The heavy items should be placed over the axle(s). The pivoting action over the axle is much less than the pivoting action in the front or rear of the trailer.
2. The items with lesser weight can be placed further away from the axle.
3. The weight on the rear of the trailer must be properly checked and controlled. Too much weight or heavy items at the back will cause excessive sway of the trailer and is very dangerous as you can lose control of your vehicle with the trailer. This should be balanced with weight in the front of the trailer
4. Also check how add on accessories fitted to the tow bar triangle like gas bottle or fire wood boxes, etc. impact the tow ball weight.
Weight Distribution Hitches: A weight distribution hitch is designed to distribute the tongue weight of a trailer across the axles of both the tow vehicle and the trailer, enhancing stability and control while towing.
1. The hitch helps to prevent dangerous towing conditions such as trailer sway, improving overall safety while driving.
2. By redistributing weight, the hitch improves handling of the tow vehicle, allowing it to maintain better steering and braking capabilities.

What Happens with Incorrect Tow Ball Weight?

Too Low: This can cause the trailer to sway excessively, which isn’t fun and can be dangerous as you can lose control of the vehicle.
Too High: This leads to overloading your vehicle’s rear and can affect steering control and braking and might lead to some extra wear and tear on your tyres. This can also lead to potentially bending the vehicles chassis as the below picture shows, when you go through a sudden dip or bump.

Legal Stuff

Stay Compliant with legal requirements: Make sure your tow ball weight is within legal limits. The maximum weight allowed on a towbar, also known as the "towball load" or "vertical load", is typically between 45 and 75 kg, but never more than 100 kg in South Africa.
Insurance: Touch base with your insurance provider to ensure you’re covered while towing.

Safety Checks

Regular maintenance and checks are essential for safe towing:

Do Regular Inspections: Make it a habit to inspect your tow ball and hitch for any signs of wear or damage before each trip. This simple step can prevent potential issues down the road.
Brake System: Ensure that your trailer’s braking system is functioning correctly and is compatible with your towing vehicle. A well-maintained brake system is crucial for safe towing.

Conclusion

Understanding tow ball weight is super important for a safe and enjoyable towing experience. By balancing your load, following the guidelines, and conducting regular checks, you’ll be well-equipped for any adventure that comes your way.

Final Thoughts

Towing can open up a world of exciting possibilities, whether you’re heading out for a weekend getaway or a longer road trip or overlanding. With the right knowledge and preparation, you can ensure that your journey is not only safe but also enjoyable without unnecessary hiccups. So, gear up, hit the road, and enjoy the ride!

Happy and Safe Towing!!