Some Helpful Tips on the Dynamics of Towing a Caravan.

Weight Distribution

The way a vehicle's total mass—including passengers, luggage, and a caravan—is spread across its points of contact with the road—the axles and tyres—is called weight distribution. So that no single point is carrying more weight than the others, it’s always best to try and distribute the load as evenly as you can.

Every vehicle has an optimal balance, which is usually around 45 per cent of the vehicle's mass over the front wheels and 55 per cent over the rear wheels. The dynamics change however when weight is added. This is factored into the design of your car, but some scenarios can cause weight balance issues.

Hitch Up Your Caravan

One of those scenarios is adding weight behind the rear axle of the car, which is exactly what you do when you hitch up any kind of trailer, particularly a heavy one like a caravan. By increasing weight behind the rear axle, you’re creating a lever where the back wheels of the car become the pivot point. As more weight is applied to the back, the front lifts like a seesaw.

If the downward force, or nose weight, on the towbar is too light due to a lot of weight being loaded at the back of the caravan, the opposite effect can happen, and the rear of the car might start to lift.  How firm the suspension is does not affect weight distribution.

Check the Nose Weight

Your caravan’s nose weight is the downward force it exerts on your tow bar. Getting the nose weight right is important for safe towing so you do need to check it. 

To find out what the correct nose weight is, you need to find the lowest of the three figures given by the caravan chassis manufacturer, the tow vehicle manufacturer, and the towbar manufacturer.

If you find that your nose weight is either too light or too heavy, you'll need to reorganise some of the load in the caravan, transfer some items to the towing vehicle, or leave anything unnecessary at home.

Correct Uneven Weight Distribution

One of the things you cover when you learn to tow a caravan is how important it is to distribute weight properly. If the weight is not well distributed, there are basically two ways to correct the imbalance. 

The first is to make sure you don’t overload the car's rear end—that could mean you have to buy a bigger car or a lighter caravan. The second is to take less with you and avoid attaching heavy accessories—like huge toolboxes or motorbike racks—to the front or back of the caravan.

Use a Towing Stabiliser or Weight-Distribution Hitch to make towing safer. However the use of these tools does not reduce the need to have the correct combination of car and caravan, nor the need to load the caravan correctly.

The easiest way to check you have the balance right is to look at the height of the front wheel arch. It should be the same, or just slightly lower, both with and without the caravan; remembering that, because there is more weight on the car, the rear will also sink a little. If the wheel arch is considerably higher, your balance is off and will need to be adjusted.

Get the Balance Right

The caravan's ability to brake effectively is severely hindered if there’s so much weight on the back that the front end is coming up.

Learning how to distribute weight in a caravan will also help to avoid sway. With the weight correctly balanced, the caravan will have a harder time pushing the car around and the car’s steering will feel better. This makes it much easier to handle and it takes less of a toll on the tyres.

Caravan Sway

Caravan sway, also known as snaking, is one of the most unnerving experiences you can have while driving, and it can be dangerous. No amount of sway is safe, no matter how small it seems.

When a caravan sways, it’s actually going faster than the car that’s towing it—this is because it’s following a swerving path while the car is still going straight. Understanding and dealing with sway is relatively simple once you understand this concept. 

Why a Caravan Sways

All caravans have a propensity to sway when being towed, due to undulations in the road, crosswinds, or, more likely, the impact of lorries and heavy vehicles overtaking. If there is a lot of weight at the back of the caravan, but the nose weight is correct, there is a high likelihood there is nearly as much weight at the front.

Having a lot of weight loaded at the front and back of the caravan can cause a dumbbell effect known as ‘Yaw Inertia’. Because the two areas of weight are further away from the pivot point, swaying tends to increase rather than be lessened by the force of the towing vehicle 

To minimise yaw inertia, you need to position the load closer to the pivot point. This might be as simple as laying the awning on the floor above the axle, but it could also mean that you have to remove some of the heavier objects and store them in the car. Generally, the lighter the caravan and the heavier the car, the easier it will be to tow.

Momentum

There can be several reasons for a caravan going faster than the car that’s towing it. The most common is if you brake when you’re going down a hill since the caravan’s momentum will want it to continue moving forward at the same speed. All it takes then to cause it to sway or swerve is a gust of wind or a bump in the road.

Balance the Load

Another situation when a caravan may sway is if the load is concentrated at the ends. It will depend on the style of your caravan but as much as possible, it’s always a good idea to pack the heaviest items over the acles. If you can, shift some of the load to the tow vehicle. Heavy items like bikes might be best put on the roof of the car.

The ideal outcome is to balance the caravan so that around 10 per cent of its total weight is on the tow ball when it's being towed, although it’s fine to go a little over or under this.

Make Sure the Caravan Is Level

Caravans perform best when they are level. As soon as the nose starts to move up or down, you're shifting weight to one of the car’s axles and reducing the contact it has with the road.

Reduce Speed

Another way to stop swaying is to slow the caravan down. You’ll sometimes hear drivers say that you should accelerate to get out of sway, but this is bad advice that will increase your chances of having an accident.

Stick to the speed limits for towing a caravan and use the caravan’s electric brakes to reduce its velocity until it matches that of your car.

How to Tow a Caravan Safely

The government provides some useful information to tow a trailer or caravan with a car plus safety checks that you may find useful.