Product Review No 6 - Tyre Pressure Monitoring Systems (TPMS) - Sensatyre & Tyredog Systems

Monday, Dec 27, 2010 at 01:00


Questions about Wireless Tyre Pressure Monitoring Systems (TPMS) appear quite regularly on many popular vehicle and travel forums. I have had a few opinions over the years in respect to various tyres of TPM systems. For the serious traveller, I believe they are an invaluable asset. With todays modern 4x4 tyres costing many hundreds of dollars each, if a TPMS saves one expensive tyre from replacement, it has all but paid for itself, mind you I’m probably preaching to the converted here. They also add a degree of safety when towing as quite often, a tyre situation a good deal further away than the vehicle cabin can go un-noticed until some real damage or danger occurs.

I own both a set of Sensatyre (on both my Nissan and the new ute) with internal sensors and a set of Tyredogs with a valve mounted sensor that can be screwed on and off the tyre valve stem. Both are multi vehicle combinations. I have 8 sensors on the Sensatyre system to cover the vehicle, trailer and two spare tyres. I utilise two external receivers at the front and rear of the vehicle. The Tyredog is set for 6 tyres being vehicle and trailer with two receivers again.

I am a big fan of the internal mount sensors as they are largely protected from external damage. The internal sensors take two forms. One is a unit incorporating the valve (so it sits inside the tyre immediately behind the valve. The second is a clamp unit that fits to the centre of the rim with a large spring steel wind on clamp (like a giant hose clamp). The external sensors such as the tyredog, simply screw onto the top of the valve stems replacing the valve cap. You can also fit a locking ring which uses a small grub screw to hold the ring and sensor in place on the valve stem and prevents them from unwinding.

Obviously screw on sensors provide added ease of functionality for rotating to other wheels. The irony is that these come with a locking fixture for safety and theft prevention. Unfortunately it means a bit of extra work with a small allen-key to remove them. If you do not use the locking rings with the cap sensors, they can be susceptible to corrugations, rocks and rough road conditions. This means that the unit can loosen from the valve and or the entire cap from the sensor unit can come loose and depart leaving the sensitive internals and battery exposed. Similarly, if undertaking rough off-track work, the caps can suffer at the mercy of the surrounding bush and terrain. I would recommend having short valve stems fitted to tyres. I have heard of another remedy in having second valves fitted in the centre of the rims. This means drilling the rim and fitting an extra valve out of the way of scrub and the likes. It seems like a hell of a lot of trouble to me and may have some impact on warranty of the rims and insurance issues should they be needed (structural integrity of the rims compromised by alteration from engineered standard – you know the drill)

I had a bad time with the Tyredog valve stem mounted units in 2009 due to rough terrain. I must add that normal highway use wouldn't have seen these issues with valve stem mounts. I found that with some remedial action in this year’s trip by;

1. fitting small valve stems on the rims; and
2. wrapping electrical tape around the caps,

All sensors remained attached, intact and operating.

Some other valve mounting systems have a sealed sender unit (TPMS brand for example). While this offers a degree of robustness, it does not allow for the changing of internal batteries. This results in the entire unit having to be replaced every three years or so at a cost of $50 per sender unit. I have no experience with the TPMS but have seen positive reports from forum members regarding the product

Visual display units provided for both products are good with windscreen mounted receivers and display. Both units utilise a cigarette plug attachment for power and a suction cup mount windscreen mount. The Sensatyre is a bigger unit but comes with a flexible mount system that was very robust and provided more mounting options. Both can be hardwired into the electrical systems of the vehicle, something I have done with the SensaTyre unit on my current vehicle.

The Tyredog has an inbuilt receiver aerial while the Sensatyre offers two solutions. First there is an external areal that screws to the top of the display module. This can be screwed on or off at will or will flip down out of the way. The SensaTyre also allows you to mount and run various wireless receivers underneath the vehicle that hardwire back into the display unit. The larger kit comes with sensors and connecters that can be mounted under the vehicle and caravan/trailer for better reception. The aerial is also great redundancy if, like I did on one occasion, severed the wire from the receiver under the vehicle. Reception on the Sensatyre was better than the Tyre-dog, particularly over distance. Display options are both good. One fault with the Tyredog was that it displays the last reading of a unit constantly and does not alert you should a sender unit be “lost” or knocked off a tyre. This gives you an erroneous reading that all is OK despite the sensor being totally missing from the tyre. Another minor issue is that scew-on caps can suffer a fair discrepency in reading internal tyre temperatures. I have noted up to 10C difference while running both sensors on the same tyre. The internal sensor provides a far more accurate reading in my experience.

Tyre dog sensors employ a small camera type, coin sized lithium battery which screws in under the cap. Easy enough to replace but I'd suggest trying to get a swag of them at a $2.00 shop if possible as the units can chew through them. The internal sensors of the Sensatyre are actually sealed and must be replaced when exhausted. The internal power lasts for up to seven (7) years in normal operating circumstances. The internal units on the Patrol were still going strong at 5 years old when I sold her.

When repairing tyre damage, Valve screw units are removed and you have no further issues. With internal mounts, you need to be mindful of the sensors. Easy enough with a valve unit as you know where the receiver is. I have found the best way is to ensure that the sender unit is actually in line with the valve. This way you will always know where the sender is located on the centre of the rim. Don’t forget to tell the blokes changing the tyres that you have internal TPMS monitors fitted.

For ease of use, I prefer the Sensatyre as they are easier to reprogram, particularly when on the move. ie Low pressure/temperature warning setting can be easily and quickly adjusted should your needs change, ie dropping tyre pressure warning settings to deal with sand or corrugations.

My personal opinion is that the quality and functionality of the Sensatyre system is better. Certainly the robustness of the sensor system is excellent as well. I have owned two Sensatyre systems over the past 6 years, each have which have done many thousands of tough outback kilometres and I have not had any issues other than damage I caused to a remote receiver. I simply changed to the aerial and all was well. The valve cap system is also a great unit for road applications. I have had issues in rugged terrain and rough, corrugated roads. The head unit is also not as robust as the Sensatyre unit.

I would also speak highly of the level of customer service from the distributors at Hannibal in QLD who will readily go through any issues over the phone while you're on the road. Price for both is much of a muchness.

A disclaimer of sorts;

I make the clear distinction here and now that while I have some experience as an outback traveller, I am not a technical expert by any stretch of the imagination. It's my personal experience upon which I base my reviews. As in this case, I will on occasion compare these products against a similar product that I am familiar with through personal experience. This is factual based and not anecdotal (someone telling me about it) experience.

These reviews are not designed to influence you towards any particular product. I’m not receiving any financial advantage in doing this, rather I am providing my personal opinion on the quality and suitability of the products I have purchased and used. Any decision about purchasing a product should be made after a thorough analysis of your own needs and budget and supported by your own research (as were mine).

''We knew from the experience of well-known travelers that the
trip would doubtless be attended with much hardship.''
Richard Maurice - 1903
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