How much pressure in air bag when towing ??

Hi Brian. I have new airbags in my Patrol. I have been told maximum pressure is 30 psi. My van is 2500 kg but have no idea what weight is on the tow ball. I have plenty of weight in the rear of patrol 240 litres of fuel, 60 litres of water, fridge, camping gear etc. I usually run 25 psi in the airbags. Have a good trip, but it is what you make it yourself.

No matter what pressure you put in them, make sure you inflate them before you load your vehicle not after. If you read the instructions for Polyair bags that's what they say.

Start with the vehicle empty, , measure the distance of the top of the rear wheel arch to the ground, load the vehicle with what is a normal load for you, measure the distance again, unload, and inflate air bags, then re load your vehicle. If the wheel arch is the same distance from the ground as when unloaded you've got the right pressure. If not unload and apply more pressure to the air bag. Once you've got the vehicle level make sure you know what that pressure is, then you make sure you maintain that pressure in the airbags.

If you try to pump up the airbags when the vehicle is fully loaded you could blow the air lines or the connection between the airlines and the bags. Also, make sure there is some air in the airbags at all times when unloaded.

When loaded up for travel, I ran my Polyair airbags at 20PSI to suit my 80 Series but I did not include the weight of the towball when towing. I used a weight distribution hitch (WDH) to level the vehicle up when the caravan was attached. I'm not getting into any debates about the use of WDH's that's for you to decide.

WBS

Many thanks again , great site , great people

Hi Brian,
Also if you use a bike pump to inflate the air bags you can do a lot better, as you only need small amounts of air to change pressure. That way you can do it in small amounts until you get it right.

David.

Brian,
If the air bags are red, they could be Pedders ones, require a minimum of 5psi to a maximum of 30psi.
As suggested, pump up before loading, if vehicle not level, just release a SMALL amount of air out till you are at the required height.
Cheers.
baz

Brian,

I don't think that there is one pressure that fits all...

I was told that the best way to find what pressures your bags require is to hook up the fully loaded vehicle to the loaded van, normally the tail of the vehicle and front of the van drops.

Wind up the jockey wheel until the vehicle and van are at the required level, then using a foot pump or compressor, pump up the airbag on each side evenly until the jockey wheel becomes “light” just use the jockey wheel winder to check this.

Then check that the vehicle is level left to right (fuel tanks, fridges and loading can make left or right heavier that the other side. Wind up the jockey wheel and check what pressure is in each bag.

This will vary on every vehicle/van combination.
Before you hook up and when you go to fuel up before a trip, inflate the airbags to the known pressures, don’t forget to drop the pressures when unhooked.

Good luck.

Well i started off by erring on the side of Caution by putting 25 psi in , made van very out of level (tilting towards the back ) so i drove for a while very cautiously and van began to Wobble , so stopped deflated bags a bit , van ride was a fair bit better but still dipping at the back , will check pressures tomorrow , might have to consider a WDH ?

Thanks Batt , found that i could reverse my tow ball , undid split pin ,knocked out main pin and took out tow bar square shaft and took ball off reversed the shaft put ball back on which meant my tow ball is aprox 4 inches lower, ride is great now , thank you every one again