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Load: regarding light trailers and the car’s weight

Correct loading

The following 3 points are the basis for correct loading:

  • Secure the load with a strap or similar. Unsecured loads which slide around can be thrown and cause major damage in the event of forceful braking or a collision.
  • Position the load far forward (as close to the front as possible) so that it will not come loose and fly away. If the load is already tucked right in against the back seats in the boot, it has nowhere to go in the event of forceful braking.
  • Position heavy loads low in order to reduce the risk of them being thrown and causing damage.

Normally, it is during braking that the greatest stresses on the load and fastenings arise. This means that the fastening must at least withstand:

  • 80% of the cargo weight in a forward direction.
  • 50% of the cargo weight in a backwards direction and to the sides.

If you have loaded a refrigerator weighing 40 kg onto a trailer, the straps must withstand a minimum pressure of 32 kg (80% of 40) in a forward direction and 20 kg (50% of 40) in the other directions.

Weight terminology

  • Unladen weight: Unladen car with standard setup including driver (75 kg).
  • Maximum load: Maximum permitted load in accordance with the registration certificate.
  • Total weight: Unladen weight + maximum load.
  • Gross weight: The weight at a given time.

Light trailer

With a category B licence, you are only allowed to tow a light trailer. The matter of which trailers are classed as light is often determined by the weight of the towing car.

Note that there is a difference between what is classed as a light trailer and whether or not the car is permitted to tow the trailer!

What counts as a light trailer?

  • Trailer with a maximum total weight of 750 kg.
    or
  • Trailer where the maximum total weight for car + trailer is 3.5 tonnes.
    • The requirement for the trailer’s total weight not to exceed the car’s unladen weight was removed in 2013.
Trailer, example 1
Trailer The trailer’s total weight is less than 750 kg and is therefore classed as light.

No calculations need to be done.
Total weight: 600 kg

Trailer, example 2
Car Trailer
Total weight: 2,100 kg Total weight: 1,400 kg
Calculations must be done, as the trailer’s total weight exceeds 750 kg.

The combined total weight (2,100 kg + 1,400 kg = 3,500 kg) is 3.5 tonnes exactly, but does not exceed 3.5 tonnes.

This means that the trailer is classed as light.

Trailer, example 3
Car Trailer
Total weight: 1,800 kg Total weight: 2,000 kg
Calculations must be done, as the trailer’s total weight exceeds 750 kg.

The combined total weight (1,800 kg + 2,000 kg = 3,800 kg) exceeds 3.5 tonnes, which means that the trailer is not classed as light.

Is the car permitted to tow the trailer?

In practice, the above calculations are seldom necessary. All of information you need is found in the car registration certificate:

Swedish car registration certificate.

The car with this registration certificate is permitted to tow a trailer weighing a maximum 1,500 kg, though not with a regular category B driving licence, as O.3 stipulates that the maximum trailer weight for a category B driving licence is 1,440 kg.

Am I permitted to use this car to tow a trailer weighing 1,600 kg with the extended B category or BE licence?
– No, as the maximum weight specified in O.1 may never be exceeded, regardless of category. The car is not built to handle heavier trailers.

Ball pressure

Ball pressure is the pressure which the trailer’s coupling device exerts on the car’s towbar. Normally, the ball pressure should lie somewhere in the interval 30–100 kg.

High ball pressure

Excessive load at the front of the trailer. This gives poor traction with the front wheels and makes the dipped headlights dazzle.

High ball pressure
The load is all the way forward in the trailer (the red box) and is therefore pressing the coupling device towards the ground. The car is forced to follow it, and since the car is straight, the front end is elevated.

Low ball pressure

Excessive load at the back of the trailer. This gives poor traction in the rear wheels. Can lead to a driving ban.

Low ball pressure
The load is placed far back in the trailer (the red box) and is therefore tipping the trailer backwards so that the coupling device is pushed upwards. The rear of the car is lifted by the coupling device.

Regulations concerning trailer brakes

  • A service brake must be fitted on trailers with a total weight exceeding 750 kg.
  • A parking brake must be fitted on trailers with an unladen weight exceeding 400 kg.

Marking heavy lorries and heavy trailers

Reflector on a heavy lorry:

Reflector on a heavy lorry

Reflector on a trailer with a total weight exceeding 3.5 tonnes:

Reflector on a trailer with a total weight exceeding 3.5 tonnes

Practice theory tests

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Last updated 2018-10-23.