Roof bars are a great way to transport large and bulky items that take up too much space inside your vehicle. However, they are not designed to carry heavy weights, and if you do, you will likely damage your vehicle and risk a serious accident. Most four wheel drive only support a maximum of 100kg on the roof racks. Some full-length steel gratings weigh around 50kg, and their load-bearing capacity is drastically reduced as a result. A few drums and you are already thinking about exceeding the limit. It is important to ensure that the total weight on your roof does not exceed what the manufacturer indicates as a maximum.
Not all racks weigh 50 kg; many do not weigh more than 15 kg. However, it depends on the design and materials used. What’s just as important as checking the maximum load your roof is designed to support is seeing what your roof bars will carry. Some roof racks are only designed to carry 30kg each and again these can easily be overloaded. Also take note of the conditions in which the racks are designed to operate. I have seen numerous roof racks that say “not for off-road use”. If you get a set like this, put a few drums on top and then ride over gravel, sand, or other bumpy roads, you risk damaging the racks, losing your cargo, or damaging the roof of your vehicle.
It is very common to see people loading their racks with more equipment than they should carry or loading the roof with more than they should carry. Again, keep heavy items in your vehicle and large, bulky items on the shelves. By doing this you ensure that the center of gravity is kept low and this makes the car more stable. When driving a four-wheeler, this is of the utmost importance. Even when you’re on the road, it’s much safer to have a lower center of gravity.
The main reason why roof bars are rated for different weights is their design and the material that is used. You will find that plastic grates will generally not be able to support as much weight as steel or aluminum. Aluminum is lighter than steel, which is useful if you want to haul heavier loads on top (again, I don’t recommend this!)
