Loading a car and towing a trailer

Whose responsibility

The driver’s, always. It does not matter who loaded the vehicle. You are responsible for making sure it is not overloaded, that the load is secure, and that nothing projects dangerously.

An insecure or excessive load is an offence, and it can invalidate your insurance.

Where the weight goes

In a car, heavy items go low and central — in the boot, over the rear axle rather than behind it, not on the parcel shelf.

Anything loose in the cabin is a projectile. In a 30 mph impact a laptop on the parcel shelf continues at 30 mph until something stops it, and the thing that stops it is usually a head.

On a roof rack, weight raises the centre of gravity. The car rolls more in corners and is pushed harder by crosswinds, and drag increases substantially. Remove empty racks and boxes when you are not using them.

On a trailer, heavy items go low and just ahead of the axle, so there is a modest downward force at the coupling — the nose weight. Too little nose weight and the trailer becomes unstable; too much and it overloads the back of the car and lightens the steering. Both the car and the towbar have a maximum, and both are in the handbook.

What loading changes

• Stopping distances get longer. More mass, more energy for the brakes to turn into heat, and a greater risk of brake fade on a long descent.
• Cornering changes. More roll, and less warning before the tyres let go.
• Steering may lighten if weight is over the rear.
• Tyre pressures usually need increasing. Most handbooks give a separate set of laden pressures — and an under-inflated tyre under load overheats and can fail.
• Headlight aim may need adjusting if the car has that control.

Towing

Towing changes almost everything about the vehicle.

• Lower speed limits: 50 mph on a single carriageway, 60 on a dual carriageway or motorway.
• No right-hand lane on a motorway with three or more lanes.
• Much longer overtakes, and wider turns.
• A breakaway cable must be attached, so that the trailer’s brakes apply if it becomes detached.

Snaking

If the trailer begins to swing from side to side, the oscillation grows with speed.

Ease off the accelerator gently. Keep the steering as still as you can. Do not brake.

Let the speed fall until it settles. Braking hard or steering against it usually makes it worse and can jackknife the outfit.

Prevent it by loading correctly, checking the nose weight, and keeping to the towing speed limits.