Caravan Gross Vehicle Mass (GVM) & Tare Mass explained

Caravan Gross Vehicle Mass (GVM) & Tare Mass explained
By Willie Bromehead & Mark Lowe

Weight ratio balance between your car and caravan is important, as it is critical in ensuring the stability of your car and caravan whilst towing. 

The best weight relationship for safe towing is that the actual laden weight of your caravan should be about 85% of your car's kerb-weight. This is recommended especially if you are new to towing. In other words, the Gross Vehicle Mass (GVM) of the Caravan may not exceed the Licence Mass (unladen and without driver or passengers) of the towing vehicle. All motor vehicles, cars, station wagons, LDV’s and 4 x 4’s, are also subject to the Tare and GVM rule.

You can find out the weight of your car and caravan by checking these figures in your handbooks. If you do not have your car or caravan handbook, a phone call to your local motorcar and caravan dealer to ascertain the weights is all that is necessary. 

There is also a small plate that is located on the A-Frame of your caravan. This will tell you the gross vehicle mass (GVM) and the tare, with the difference between the two figures being the load weight that your caravan has been designed to carry. 

Where you position the items inside your caravan when towing is also important for the stability of your caravan. Heavy items, such as tent and poles, additional refrigerator etc. should be placed directly over the axle of the caravan, and as low down as possible. Do not place heavy items in the overhead lockers as this will affect the caravan’s centre of gravity and result in stability problems.

Heavy items as above should be secured as tightly as possible to prevent them sliding around whilst on the move which could alter the balance of the caravan such that inherent stability and/or centre of gravity is compromised.

If you load too much weight onto the nose of your caravan this will put additional strain onto the car or caravan chassis, which could lead to expensive repair bills! The ideal nose weight of the caravan should be between 75kg and not exceeding 100kg and can be measured using a bathroom scale and thick wooden beam sized at the normal height of the tow bar. 

Overloading the back of your caravan can also cause problems with safety and stability. You may find yourself in a snaking situation that is when the caravan takes control of the steering, which will result in you being unable to keep control of your car and caravan. 

Placing heavier items in the boot of your motorcar will not exempt you from this rule. You will only aggravate the situation by placing too heavy a load at the rear of your motor vehicle. This will apply to motorcar and station wagon, as well as LDV’s and 4 x 4’s. Increasing the weight of your motor vehicle will not compensate for a lighter load in the caravan as some people are under the misguided conception. 

The “Tare” (the weight of the caravan which subtracted from the Gross weight, or total laden weight gives the net weight.) of your caravan is: - standard caravan in "road-going trim" but without the following items:

• Tent and poles.
• Crockery.
• Battery.
• Gas bottle/s.
• Water bottle/s.
• Spare wheel.

The additional weight of tent, poles, crockery, battery, water bottles with water, clothing, food, kids toys and any item loaded into the van, all added together and added to the Tare, will give you the GVM, (Gross Vehicle Mass) of your caravan. 

I know it is impractical to try to weigh every item as you load, and probably the only ‘sure fire’ way to ascertain if you are within the legal limits, is to load the caravan and head for the local weigh bridge! Not only impossible and unrealistic, but at least try to gauge your load as you pack. 

If, whilst towing, you feel the slightest sway or snaking, stop immediately and double check your load balance. A re-shuffle will not only relieve the situation, but will definitely ensure a safer journey.