Limits of Roof Racks
There is a limit to what your vehicle can carry. This is not set by the roof rack. Rather, it is set by the vehicle, and the roof rack has to work within this limit. On average a moving vehicle might carry 100 kg, including the weight of the roof rack. So it is in our best interest to keep the weight of the roof rack as low as possible, whilst keeping it strong enough to support the load on the roof.
Of course, 100 kg is only an average. We should look at the load for our particular vehicle. This should be in the vehicle owner’s manual. And then we should understand how this changes in the situation we are in. The quoted maximum load figure applies to a moving vehicle on a typical paved road.
Situations for Roof Racks
There are three general situations for a 4WD vehicle, and the maximum recommended load varies with these situations.
On Road Maximum Limit
This is the limit given in the owner’s manual. It refers to the maximum load when the vehicle is being driven under normal conditions. This means a moderate speed on a paved road.
If we exceed the maximum limit on a roof rack we badly compromise the handling of the vehicle. This means the steering and braking will be badly affected. It also means the center of gravity will be higher than normal, so there is a risk of the vehicle tipping over when turning.
The weight issue is not simply a number. The position of the weight on or in the vehicle is important. A moderately heavy weight on the roof rack will have a bad effect on the vehicle’s center of gravity. The same weight inside the vehicle will have much less effect, as the center of gravity is lower down.
Static Load
When the vehicle is parked the load on the roof is less of a problem. A parked vehicle does not turn corners or run over bumps. So we can often increase the load by double or triple.
It might seem that a higher load when we are parked is basically useless. Why have a heavy load when the vehicle cannot move. But it is an advantage for a roof-mounted tent. If the tent and roof rack weighs less than 100 kg we can drive the vehicle on the road. And when the vehicle is parked we can have two people sleep in the tent.
Off Road Maximum Limit
A 4WD will undergo a lot of strain when driven off-road. It is best to keep the roof rack load lower than usual. 60% of the on-road limit (on average 60Kg) is a good estimate.
Recommended Standard for Racks
- Low weight with high strength
- Non-corrosive material – aluminium, stainless steel, powder coated steel.
- Aerodynamic, to reduce wind drag and fuel consumption.
- Many tied down points to secure the load with a rope.
- Low to the roof, to provide better overhead clearance and a lower centre of gravity.
- Solid welding and construction.
Looking for Roof Racks in Melbourne?
A good roof rack lasts decades and allows you to carry boats, tents, solar panels or just more luggage.
