One of the most important parts of four wheel driving is ensuring that you have the right tyre pressure for the speed that you are travelling and the terrain that you are on. For example, when driving through soft sand you want your tyres to be in between 12 and 20 PSI, as a pose to the standard 30 – 45 PSI that they should be when you are travelling on road.
One of the biggest hassles with having to let your tyres down though is that it can take a lot of time, and it isn’t exactly the most comfortable thing to do.
If you are someone who still uses keys or a stick on the ground to push the valve stem in, you are wasting your own time. Of course, this is cheap and relatively easy, but it usually takes around 1 – 2 minutes per tyre (depending on the size of the tyre) to let it down to the desired pressure. On top of this, you have to kneel there the whole time that the tyres are being let down.
Today, there are a number of alternatives which allow you to screw them on and then leave them or at least to let the air out faster. Some of the more common Tyre Deflators include the ARB EZ Deflator, the Staun Deflators and the Ferret Tyre Deflator. Each of these vary in one way or another, but they all make deflating your tyres much easier.
If you have four big tyres to let down and you are using a key to do it, you could be kneeling down next to the car for up to 10 minutes. Whilst that might not seem like a lot of time, it’s still time that you could spend fishing on the beach! Also if you are doing this every day because you are travelling the country then it becomes a real hassle.
If you don’t take the time to let your tyres down to the right pressure you will not only work the engine much harder but you will most likely damage the tyres and you risk getting a puncture, which is expensive and a pain to work around. In terms of all of the 4×4 Accessories out there on the market, a good deflator should be top of the list; they are cheap and they make life so much easier.
Why do you let your tyres down?
By letting your tyres down, you are increasing the surface area of rubber that is touching the ground. The more you let the tyres down, the wider the footprint gets, and also the longer the footprint gets. What this means is that you have a lot more tyre on the ground, which translates to more traction. If you try to drive through some very soft sand with your tyres pumped up at 40 PSI you will really struggle. However, if you were to let them down to 15 PSI it would be considerably easier.
More traction aids in having less wheel spin, which is always a good thing when four wheel driving. You should be able to go almost anywhere without spinning your wheels, if you have the right line and tyre pressure. Having more traction is also very important from a safety aspect, especially when you are driving on gravel roads.
Just like you should engage four wheel drive on gravel roads as you have more traction, by letting your tyres down a little bit then you will have much greater control. Gravel is slippery enough without you running tyres that are pumped up rock hard. Of course, the amount that you let the tyres down should be based on the weight of your vehicle and the speed that you are travelling.
Unscrewing the valve stem
People have known about the ability to unscrew the valve stem in a tube or tyre for a long time, but up until recently no one made the connection of adding it to Tyre Deflators. By unscrewing the valve stem in a tyre you will deflate much faster as the air flow is not so limited. Most of the better Tyre Deflators are able to unscrew the valves.
Of course, you have to unscrew the valve by twisting it, and then you have to do it back up when you don’t want more air let out, but this is much better than having to kneel down next to the tyre for several minutes at a time. You can purchase the tools to unscrew the valve, but you want to be careful that you don’t unscrew them too much, and they can’t tell the pressure in the tyre!
ARB EZ Tyre deflator
The ARB EZ Tyre Deflator has been around for quite some time now, and a lot of the more serious four wheel drivers have them in their car. They are basically a gauge connected to a little piece of metal which you screw onto the valve, and then unscrew the valve stem.
This lets out a considerable amount of air, and by moving a piece of sliding metal up and down you can release air or stop it from escaping. It will also tell the pressure in the tyre, which is great. You simply kneel down, screw it on, unscrew the valve stem and then stand up again for about 20 seconds. Kneel down again and check the pressure, make your small adjustment and then you screw the valve back in, unscrew the tyre deflator and it’s all done.
Staun tyre deflator
Staun Tyre Deflators work in a different kind of way. You get four in a set (they are like slightly larger valve caps) and they can be adjusted to whatever pressure that you want. All you need to do is unscrew the valve caps and screw one onto each valve, and then leave them. They will let the air out whilst you just stand there, and they will go down to whatever pressure they are set to. You then remove them, screw the valve caps back on and you are done.
Unfortunately, it’s not that easy to adjust the Stauns, so you have to basically leave them at whatever you set them at. A lot of people loctite them so they can’t adjust, and then just buy several sets for different tyre pressures that are being run.
To be honest I have read a number of different reviews about these. Some people love them, whilst other people say they are no good at all. I have heard that if you don’t keep them in a secure pouch they will bounce around and adjust themselves. They are not as fast as one that undoes the valve stems, but you don’t have to check pressures and they are generally easier to use. These are also very easy to lose, and you need to unscrew them from your tyre valves before you drive around, or you will damage them.
Ferret Tyre Deflators
Ferret Tyre Deflators are something that I currently use, simply because of how cheap and small they are. You can purchase one in Australia for fewer than 25 dollars, which is by far the cheapest deflator that is any good on the market (other than a stick on the side of the road!). They are machined by a local Western Australian, and are designed to unscrew the valve stem and to let a lot of air out.
The compromise in price though means that they don’t come with a gauge. What this means is that you have to unscrew them and then check the pressure, or you need to remember how many seconds each tyre requires the valve stem to be open. I know that for mine, (it lets about 1 PSI out per second although that varies a bit for different sized tyres) I can drop my tyres right down in under 30 seconds.
If you always run the same pressures and same tyres then this thing works very well. I simply use my watch to time the number of seconds that goes by before screwing the valve back up. Of course, if you want the luxury of a gauge then you can easily get an ARB EZ Deflator, but you pay twice the price!
Correct tyre pressures
You will find that there are many different opinions when it comes to running the ‘correct’ tyre pressures. However, opinions aside, science tells us that you need to run them at a pressure that suits the weight of the vehicle, the terrain that you are driving on and the speed that you are traveling.
For example, an older, small Suzuki Sierra should run its tyre pressures at less than 30 PSI on the road because they hardly weigh anything. A big loaded up Nissan Patrol though would run its tyre pressures at over 35 PSI on the road. Please see the 6 PSI rule below to find out what the right tyre pressures are!
4-6 PSI rule – Find the right Tyre Pressure
You may have heard of the 4 PSI rule, which is exactly the same as the 6 PSI rule, except for the difference in pressure. The 4 PSI Rule is generally applied to cars, and the 6 PSI rule is recommended for four wheel drives.
The 6 PSI rule is a general guide for testing whether your tyre pressures are at the right pressure. It is not something that you should follow to the dot, but it is very handy at times. To start off with, let your vehicle sit for over 10 hours, so that the tyre temperature drops to the room temperature. Before you get into the vehicle, measure the pressure in each tyre. From there, drive the vehicle for over an hour at the normal speed that you do. Get out of the vehicle and test the pressures again and note down the difference.
As a tyre drives along it will heat up because of friction, which will result in a higher reading of pressure. If your tyres haven’t gone up 6 PSI in the time that you have been driving it then you need to lower the pressures a bit.
If it has gone up by more than 6 PSI in the hour of driving then you have the pressures too low and you need to pump them up a bit. By making small adjustments to your tyres you will eventually get them to the right pressure. Bear in mind though that for driving on different terrains you will need to adjust the pressures.
For driving on gravel you want to drop the pressure by about 10 – 15 PSI, for soft sand you want to drop it about 20 – 25 PSI and for mud and rock driving you want to have the tyres up slightly higher than for sand driving. Of course, a lot of the off-road tyre pressures should be based on the size of your tyres, whether or not you have bead locks, the speed that you are traveling and the terrain that you are driving on.
Pumping your tyres back up
Of course, for driving on roads you need to inflate your tyres back up. If you leave them at a low pressure then they will heat up very quickly, and the rubber will start to fall apart; ruining an expensive tyre. If you have to drive on bitumen or gravel on low pressures make sure you severely limit your speed and that you are stopping regularly to check how hot the tyre is getting.
It’s not that hard these days to mount a Car Air Compressor into your bonnet, under a car seat or just in the back of a vehicle. You can purchase these for around a hundred dollars for a reasonable one, and then the price goes up. If you want a serious set up you can mount air tanks under the side steps. Pumping up a bigger sized tyre should take no more than 3 minutes with a good compressor, but it is vital that you do pump it up! Alternatively, just use a totally portable compressor and pull it out of the car when you want to use it.
Beadlocks are like a tube which sits inside of the tyre, on the rim. These are usually pumped up to around 40 PSI and they basically stop the tyre from coming off the rim and they support the tyre when it is run at very low pressures. If you go too fast around a corner with low pressures in your tyres then you risk popping a tyre off the bead, which can be a real pain and may even damage the rubber.
These are illegal on road in many countries, so check the legalities of where you live! In competitions though, they are very popular as they enable you to let your tyres down to 3 PSI, which is a massive advantage in terms of traction!
What tyre pressure can you safely go down to?
In my experience, having the right type of tyre and the right tyre pressure will make the most difference when it comes to how far up the track you will get. The more you lower your tyres down the better traction you have, and you will find that you will have a much better chance of getting up that muddy hill climb if they are set correctly.
I have heard people say that you should never drop your tyre pressures down below 18 PSI, which in my experience totally incorrect. If you are stuck on the beach with the incoming tide you would do anything to get out, so drop your pressures down to 4 PSI if you have to. Obviously driving fast down the beach in a heavy vehicle with your pressures at 12 PSI is going to increase the chances of the tyre coming off, so drive sensibly.
I normally let My Hilux tyres down to 10 – 13 PSI on the beach and have never had a problem with tyres coming off. If you need to, drop the pressures down a lot and then pump them up a bit when you are out of the boggy sand. As long as you don’t turn too sharp, or power on too much you shouldn’t ever have a problem!
If you are looking for Cheap Tyre Deflators, then I would highly recommend eBay. You will get almost anything on there for cheaper than your local four wheel drive shop, as long as the freight doesn’t kill the pricing.
Happy four wheel driving!