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TYRE PRESSURE MONITORS - excellent tools


    I have talked about monitors elsewhere on our website but I’ll go through it again. Tyre pressure monitors are excellent tools. So good in fact I reckon just about everyone should have them when touring off-road in a 4WD. The monitors, if set correctly, will tell you with an alarm when a tyre is in trouble, mostly you will have time to get off the road and find a good flat spot before you need to get out and have a look for the problem. The monitors will save you money as they almost eliminate the problem of a run-flat tyre, which destroys the tyre. Just one or two run-flats and the monitors have paid for themselves. Particularly with low profile "modern" tyres & rims, monitors are the bees knees, trust me. Those travellers who always seem to have trouble with tyres for whatever reason, should have tyre pressure monitors. The lucky folk that never have a tyre problem may get away without them. As with most things it is a choice that is up to you.

    If you are shopping for monitors, get a set that also tells you temperature. This way for highway work you can use Michelin’s "4 psi rule" to correctly set your pressures whatever weight the vehicle is carrying. To explain; when Michelin were testing Radial tyres in the 1960s they found that the correct cold highway pressure was if, when going down the bitumen, the tyre went up about 4 psi due to the heat. So when you are going to work during the year with no load you should have a different pressure than when you are loaded with the family & the kitchen sink during school holidays heading for the outback.

    There are three methods you can fit monitors to your tyres & rims, but all of them have a central gizmo that will sit on your dashboard & has a read-out so you can see & hear what is going on. The first two methods described below I don’t like at all. I have over the years seen very few people proficient at working on tyres in the bush. So any monitor fitted inside a tyre is in for a rough time on the side of the road or in camp. I have even heard of plenty of tyre shops that have broken monitors while removing & mounting tyres. Many of the fellows these days have no tube experience when dealing with tyres & rims on a machine. If you do know how to handle tubes in the context of taking a tyre off or putting a tyre on a rim then you might be OK with an internal monitor.


Rim Mounted Monitors

    These have a large hose clamp with the monitor attached. You clamp them onto the "well" of the rim so obviously they can only be used for Tubeless rims & tyres. They sit inside the tyre out of harms way.

    I don’t like these systems. Firstly you can’t check the monitor, you can’t even see the monitor and if you do a tyre repair in the bush I’m guessing most folks will damage the monitor while battling to get the tyre off the rim. Another point is that if a tube needs to be fitted to help a repair then the monitor will have to be removed anyway. They will save a tyre but may cause you far more work when you try to fix it in the bush. I’ve no doubt they are a brilliant system on the highway but for our conditions in the outback I believe there are better ways of fitting pressure monitors.


Rim mounted monitor

Monitor fitted inside tyre, clamped onto rim –
prone to damage from the inexperienced tyre fitter
Image found on the internet – thank you



Valve Replacement Monitors

    This is another method of fitting monitors. The monitor has a valve stem and you fit them to the rim through the valve hole so you no longer have your standard valve stem, another system only suitable for tubeless tyres. Once again the monitor is inside the tyre and can’t be seen or checked. Again a novice working to get the tyre off the rim for a repair will probably damage the monitor and again you cannot fit a tube to help with a tyre repair. So another system that is a brilliant thing but not the best choice for the outback where things can go wrong far from help.


Valve Replacement monitor

Valve stem monitor fitted inside tyre –
prone to damage from the inexperienced tyre fitter
Image found on the internet – thank you



Screw On / Valve Cap Monitors

    I was recently looking around a few pressure monitor websites & forums and as usual I was surprised by a few things. Most of the mobs were saying that the monitors that screw onto your valves on the outside were not a great idea because they get bashed with scrub & rocks and will be damaged or lost. I thought to myself "we’ve had these on dozens of customer vehicles for many years off-road & bushbashing in the western deserts and have never had a real problem apart from the odd flat battery which is easily changed in a couple of minutes & a couple of leaking ones because they were loose. So it must be a lot rougher where these folks go........".

    After more than a decade of commercial touring I don’t take a lot of notice of forums & marketing; most of it is hot air (I’ve never been to a 4WD show!!). On the other hand someone reading this article may think this is hot air. Again it comes down to choice, experience & personal opinion. No two people are the same.

    OK, back to the monitor thing.......The screw-on jobs are just a monitor device that replaces your normal valve cap. A very simple thing that can be checked at a glance and most importantly it doesn’t matter what sort of tyre & rim you have. They work exactly the same for tubeless, tubed & split rims. They are easy to remove & replace if a battery has to be changed and from experience they seem to be a really good tool. During the last 8 years or so since monitors have become more common we have yet to damage one while in the bush. It just hasn’t happened yet. Another big complaint is that they may come loose and fall off. Well to that theory I can say that a loose monitor is a leaking monitor, so if it is doing its job then your pressure will drop and the alarm will sound, won’t it???? Stop the bus, find the loose one and tighten it up. That may have happened on our trips maybe once or twice that I recall, but we have never lost one.

    From my point of view as a tyre repairer the screw-on jobs are great for novice tyre repairers. All the different tyres & rims can be handled as normal with no fear of damaging a monitor while wrestling with a tyre & rim. The simple things are often the best.


Screw On / Valve Cap monitor

Screw on monitor fitted to valve
Easiest, simplest & most versatile system in our experience
Image found on the internet – thank you


One Problem with Screw on Monitors in Tubeless Tyres

    The only drawback to the valve cap monitors is that they can rub your rim & damage the rubber valve from being thrown onto the rim by the forces of the rotating tyre. This is more common with tubeless rubber valves as the rubber is quite flexible. If this has been happening to you the solution is really simple; replace your rubber tubeless valve stem with steel valve stems that are a lot tougher and also withstand a lot more pressure.

    I don’t have any pictures of this problem. I’ll try and get some next year.


December 2016



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