Did you know the roof on your 4WD has a weight limit? I’ve lost count of the number of badly overloaded roof's that I’ve seen while travelling around WA. Not only is it putting your vehicle and passengers at risk, it can void your insurance and cause serious problems in the event of an accident.
How do you know if you are overloaded?
There are two things you need to consider when looking at the amount of weight on your roof racks.
4WD's roof capacity
When a 4WD is designed and built, the manufacturer gives it a maximum roof loading rating. This is the maximum amount of weight you can apply to the roof of your 4WD, and includes both the roof rack itself and anything on the roof rack.
If you want to know what your 4WD is designed to carry, have a look in your owners manual or contact your vehicle manufacturer. Most 4WD's can do up to 100kg, with a few at 150kg and very few at 200kg (the new 200 Series Land Cruiser for example).
Roof rack capacity and specifications
Every roof rack comes with a maximum carrying capacity, and a set of conditions. I've seen roof racks designed to carry 60kg, but it clearly says not suitable for offroad use. Not very good when its mounted to a 4WD! Their capacity is generally reflected in the way they mount to the roof and distribute the load.
So long as you are within the roof rack and vehicle manufacturers specifications, you won't have an issue.
What does your roof rack weigh?
Something that is often overlooked is the weight of your roof rack itself. We installed a Powerful 4x4 full length steel cage roof rack on a mates Patrol a few years back, and weighed it at at around 60kg. When you can only carry 100kg on the roof, fitting a 60kg rack to only be able to carry 40kg seems a bit pointless.
For this reason, I always recommend a quality built aluminium roof rack; they are substantially lighter and just as strong. That same Patrol had the steel rack removed not long ago, and replaced with a top quality Tracklander aluminium one that weighed under 1/3 of the steel one.
Already, people are really starting to see the importance of overall 4WD weight. Anything you can do to reduce the weight on your 4WD will benefit you.
What happens if your roof is overloaded?
Excess strain on your 4WD and roof rack
Next time you are bouncing your way along a tough 4WD track, spare a thought for how your roof and the roof rack feels! If you are a passenger in a 4WD, try and hold your arms out and keep them there while you are bouncing around. It's almost impossible, and your roof cops it way worse than that.
100kg on the roof equates to a massive amount of force every time you bounce up, down and side to side. The roof will take this all day, every day, providing you are within the rated capacities.
Go over it though, and expect to see damage in time to the roof of your vehicle and the roof racks.
Higher center of gravity
Centre of gravity is super important when it comes to a 4WDing. When you are travelling on rough tracks, side angles are dangerous. A bump just beyond what your vehicle will handle can lay it on its side, and when you have over 100kg on the roof that happens so much easier. The more weight you have up high, the higher your center of gravity, and the worse the vehicle will handle.
If you've driven the same 4WD with a decent amount of weight up top and then removed it all, you will see it very clearly in the corners and general driving, even in the city.
Insurance and legal issues
Regardless of who you have 4WD Insurance with, every policy requires the vehicle to be in a roadworthy state. If you have more weight on the roof than what your vehicle manufacturer has set, your vehicle is not roadworthy and the insurance company has a valid reason to deny or reduce your claim.
Yep, lets say you have 150kg on a roof rack and roll your 4WD on the edge of a sand dune. Your insurance company has every right to say 'sorry mate, you were overloaded'. This is the same for chassis damage through overloading. Is it really worth the risk?
Beyond that, you have a 'moral' responsibility to drive a legal vehicle. If you are outside of this and you injure or kill someone, what do you think is going to happen? The blame always goes to someone, and if you caused the death of someone through your negligence (by overloading your roof racks) you could be in a terrible situation.
The less weight up top the better
Whilst roof racks might be an easy place to store gear, the less weight up top the better. Your car will handle better, have less chance of rolling over and have less strain put on the roof. Roof racks are the ideal storage area for light weight, bulky items like solar panels, Maxtrax, camp chairs, tables, tents, portable toilets, fishing rods and swags.
What should you look for in a roof rack?
Weight distribution and mounting points
There is a vast difference in quality between roof racks on 4WD's. You can pretty clearly see evidence of this based on the way a roof rack is mounted to the vehicle, how the weight is distributed and how well its clamped down.
Several years ago we hit a nasty hole on a track out the back of Dwellingup in a 4WD with a cheap set of roof racks bolted on, and the force slid the whole arrangement forward about 200mm along the gutters. Asides from a lot of paint removed from the gutters and a bit of damaged pride, life continued. However, you'll see that the better quality racks clamp down extremely well; they are intended to carry the weight safely both on and off road.
One of the better designs I've seen is to have a length of flat bar running down the inside of your gutters. Instead of the weight of your roof racks being spread over 2 - 5 mounts, it is evenly spread along the whole length of the gutter. Combine that with good quality clamps and you have a great roof rack.
Tie down attachment points
It's important to have plenty of places to attach ratchet and occy straps. There's nothing worse than having to struggle with hooks that don't fit over the support bars just to safely store your gear.
I find having a cage version all the way around fantastic, as it stops things moving forward and side to side. Whether its just strong mesh, or little hooks in convenient locations, its worth paying attention to.
Low to the roof
If seen some roof racks that have the bottom some 150 - 200mm off the roof of your 4WD. That is absolutely ridiculous in so many ways. Our 80 series racks are within 60mm, and the closer the better (except it is almost impossible to wash the roof!). You'll have less wind drag (so better fuel economy), less noise, a lower centre of gravity, more chance of fitting under car parks and trees and an easier time getting things down!
Quality welds and finish
Sure, you can buy a full size steel roof rack for under $300, but do you trust it? Steel that has been poorly painted will rust, and that ends up on the panels of your vehicle. I have a mate who is up for just under a grand to have his roof repaired from a poor quality steel rack that dripped rusty water onto his roof.
Look at the welds too; they should be smooth, have decent penetration (not look like the weld is sitting on top of the metal) and no holes or abnormalities. Any of the better known manufacturers (ARB, Tracklander, Rhino Rack etc) are good to look at, to see how things are done properly.
Static vs Dynamic weight
I'll quickly mention this, as it comes up regularly when discussing roof top tents. If you aren't moving, the weight on your roof is static. Perhaps you, your partner and the roof top tent weigh 210kg, but your vehicle is only rated to 100kg. The rating given by the vehicle manufacturer is a dynamic rating, which means its meant for when you are bouncing around on a 4WD track.
If you are just climbing up and down and sleeping in the tent you won't have an issue, unless you are well over double the dynamic rating.
What roof rack do you have, and what do you carry?
I'm keen to know what racks you guys run, and what you use them for. Also, if you've got any tips or questions, leave a comment below!