Roof top tents and load ratingsPeter Fazzini
Roof top tents are becoming more and more popular, for those people that want to discover Australia. You can sleep on your roof, staying away from those creepy crawlies.
Thinking a roof top tent is the answer? Please read on for what you need to know.
First of all, it’s not going to be possible to fit a tent on every type of vehicle. You’re going to need to get supporting racks. Your vehicle will need to have solid gutters, a track system or raised or solid rails. Generally, you need to have minimum 2 cross bars but can also be connected to platforms. Not all styles of roof racks will work. Be aware that most roof top tents have connecting u bolts and support longitudinal supports, so take note of the connectors before buying your roof rack.
It’s not recommended to put a tent onto a roof rack system that clamps into the top of the door frames.
Next up is the issue of your vehicle’s maximum load rating which the car’s manufacturer will specify. You will need to add the self-weight of the tent plus the self-weight of the roof racks (and any other gear you store on or inside the tent, to make sure you never exceed the max load rating while travelling. This is known as the ‘dynamic load rating’. If you’re heading onto dirt roads, a 33% reduction should be applied to the vehicles roof rack’s load rating.
When in a stationary position, the total weight of the tent, the occupants and any other gear inside should never be more than the general rule of three times the vehicle manufacturer’s maximum load rating for the vehicle. See example below.
Dynamic vs Static Loads
Dynamic is when you are driving your vehicle and there is motion. The load ratings applied to products by roof rack manufacturers and the car manufacturing are for when you are driving the vehicle on sealed roads, i.e. they are dynamic load ratings. If you’re heading onto dirt roads, a 33% reduction is applied to the vehicles roof rack’s load rating.
Example: Roof Rack and car manufacture max load rating 75kgs, roof racks self-weight 5kgs, tent weighs 45kgs
Bitumen Roads: You have a spare 75kg-45kg-5kg = 25kgs capacity, to carry extra gear on your roof
Dirt Roads: 75kg (reduced by 33%) = 50.25kg–45kg–5kgs = no extra carrying capacity on your roof racks
Static is when your vehicle is stationary. You have a spare 75kg x 3=225kgs-45kg-5kgs – weight of 2 x bodies, say 80kgs each=160kgs = 15kgs, so your racks are sufficient carrying limits.
There are exceptions to this, which all responsible roof rack manufacturers should make you aware of, so keep up to date on the rack manufactures websites. This should never exceed to load rating as outlined by the vehicle manufacturer.
Rack manufacturers have a blanket exclusion of all rubber mounted clamp mount systems for use.