TyreInfo

Discussion, information and helpful updates on everything tyres.

When Quality Matters

Monday, January 09, 2017

There is a saying that sums up the feelings one gets looking back at a purchase or acquisition based solely on price.



When dealing with tyres the importance of this facet of procurement cannot be overstated.

A tyre is a complex machine made up of numerous different components which all have to work harmoniously as a single team, sorry tyre.  If any of the component parts do not interact or pull their weight then it’s almost certain that the tyre will fail prematurely, sometimes catastrophically.

I hear the questions already “Procurement has purchased these tyres what can we do, how can we get the most from this poor investment decision?”

Even with a low quality product if the maintenance is high quality then positive benefits may be realised.

The very first thing a tyre needs is the appropriate volume of air to support the load at the given speed.  It is expressed in TYRES 101 that the first three rules of tyre maintenance are:
1. Get the inflation levels right
2. Maintain the appropriate inflation levels
3. See rules 1 & 2

Everyone knows a flat tyre does not carry any load, but how many people actually check their tyres before commencing a journey?  Most just ASSuME that their tyres are “right”.  A quality vehicle inspection program will ensure that tyre pressures are included in the pre start check or that there is a system in place to verify the tyre inflation pressures are in the correct range for example a Tyre Pressure Monitoring System (TPMS).

Even the very best quality tyre will be compromised and degraded rapidly if the inflation pressures are not set and maintained to the expected load and speed requirements.  Buying a high quality tyre is not necessarily the answer, but maintaining your tyres goes a long way towards achieving the best returns from the investment made in the tyre(s).

For tyres which endure high loads and possibly high speeds there is another quality that is mostly overlooked.  This quality is critical to a tyres success, if the quality is not maintained at acceptable levels then even a well maintained high quality tyre can suffer.  The quality of the air delivered to the tyre is most important.  Many organisations provide nitrogen systems; at TyreSafe Australia we deliver 95% of those results with less than 20% of the costs.

Nitrogen is usually delivered in bottles or provided on site by a pressure swing adsorption (PSA) unit which extracts the 78% nitrogen from the dirty compressed air delivered by an air compressor.  

In the process of extracting the nitrogen all the moisture, oil mist and particulate contamination is removed so that only dry clean gas is delivered.  Most smaller commercial PSA units do not deliver the purity of nitrogen required to reduce the risk of explosion to below the threshold required.  If the tyre service crew even top up a tyre with normal compressed air all the benefits are lost.

“Why is this so important” is oft asked.  I question mechanical maintenance personnel about the quality of oil delivered to a machine.  New oil is normally delivered with a 10-micron count.  In some cases, lubricating and hydraulic fluids are put through a dialysis (kidney loop) machine which use the same principles as those used for provide clean blood to the human body for those who suffer kidney failure) and then the oils are returned to the machine with a particulate size of less than 2 microns.  The advantage gained is that the machines or hydraulic systems enjoy a longer life at a little extra cost.

If dirty air is delivered to a tyre, especially tubeless type tyres, the performance of the tyre will be compromised.  Any small amount of hydrocarbon (oil mist from compressors) will attack the halo-butyl rubbers that tyre manufacturers use for the liner (or tube) of the tyre.  Any compromise of the liner will permit the inflation medium to permeate through the tyre’s structure to the atmosphere, ergo the tyre needs to be constantly inflated.  Moisture forms a different issue for high performance tyres in that when water changes state (i.e. from liquid to gas/steam) it expands in excess of 1600 times.

TyreSafe Australia has direct experience where a 22.5” tyre working at the upper end of its operating range was inflated to 135 psi cold.  Using tyre pressure monitoring systems (TPMS) the pressure was observed to be regularly in the 180 – 190 psi range, yet the tyre was not overloaded, nor was the vehicle over speeding.

On inspection of tyres which had been removed from service it became obvious that the quality of the compressed air was such that there was a discernible volume of water delivered on initial inflation and at each subsequent inflation top up.  The tyres were being pushed hard, working in the 70O – 90OC range with some going over 100oC by direct tread/belt measurement.  The water was simply following what it always does and changing state.  Once the quality of the inflation medium was addressed by delivering high quality air the over pressure problems simply disappeared.

If only 43.5 ml of water is included in air used to inflate a tyre then with an expansion ratio of 1600:1, 43.5 ml of water will expand to nearly 74 litres of gas (steam) at 100oC.  This is what influences the operating pressures in tyres that are working in the upper reaches of their capabilities.

Quality does not stop at the point of purchase where tyres are concerned.  If the maintenance applied to a tyre is not the highest quality available then the tyre user is not gaining the maximum return from the tyre, which leads to a previous question, “why are you throwing money away?”

It makes no cents to ASSuME, remember that monitoring, measuring, maintaining, makes money!
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Tyre Temperature versus Tyre Pressure: Which gauge to use?

Monday, December 19, 2016

I am often asked about tyre temperature. In response, my direct question is “What is the temperature you are attempting to measure?” “Well tyre temperature of course”. When asked “what section of the tyre are you thinking of measuring” is usually met with blank looks. Tyres are composite construction, they are made from various and quite different rubbers, fabrics and steel in varying configurations. A race car tyre has a very lightweight construction compared to an OTR (mining) tyre and looks for traction as the ultimate property whereas the OTR tyre seeks load and life as prime qualities. The tread face of a racing slick may exceed 400˚C during hard braking. If an OTR tyre exceeds 150˚C at the tread belt interface it will more than likely suffer a heat separation and potentially fail catastrophically. A passenger car tyre can be sitting in the sun and rise tens of degrees without actually doing any work.

Many non‐tyre people relate to the ideal gas equation that relates exactly for rigid pressure vessels,we know the P1V1/T1 equation and I suggest it seems that this equation doesn’t exactly relate to composite flexible pressure vessels also known as tyres. The variance in a tyre’s volume during operation throws the calculation into chaos. Yes, a tyre is elastic, stretching and constantly being reshaped in response to load, speed, the interaction with the pavement, add friction, and the calculation becomes horrendous. Major manufacturers have all attempted to establish the correlation but it has continued to allude those who seek this Holy Grail.

The concept that a tyre’s cold pressure can be calculated from a hot pressure of fraught with unknowns and external influences such as wheel hub heat, brake radiant heat, being on the sunny side of a vehicle. The list of variables grows not to mention air quality but that’s another story for later.

At a point the person asking for temperature realises they have walked into a Tardis like situation where what appeared to be a simple external appearance takes on complexities of ever increasing magnitudes. Eyes widen and expressions indicate realisation that the Rumsfeld principle had hit home, they don’t know what they don’t know.

A tyre of any size is a container for the inflation medium. Whilst there may be macro variances within a tyre’s air chamber resulting from fluid dynamics and thermodynamic activity the pressure acting on the valve stem remains consistent, of course it varies as the tyre works but the applied pressure on the valve stem remains consistent (agreed not static!).

Think of a pimped up car with bling spinner wheel covers, you know the ones that keep spinning after the vehicle has stopped. Now, think about the air inside the tyre that has its own inertia and mass and will keep on moving even when the tyre is at rest until it consumes the inertial energy imparted by the motion of the vehicle. This motion causes eddies and vortexes that influencetemperatures and macro pressures, there are situations of partial pressures. When a giant OTR tyre stops turning the hot air will rise to the top of the air chamber as the laws of convection apply. Even in a TBR tyre, this is easily measurable.

Rubber is an extremely poor conductor of heat, with a heat transfer rate magnitudes lower than metals. This phenomenon is what permits the racecar tyre to survive the tortuous nature of having rubber applied to the pavement chasing traction. Rubber will commence reversion in a small temperature range about 105˚C when measured at the critical point between the belts and tread.Tread face and air chamber temperatures may be related as is the tread/belt interface but measuring it is a physical impossibility with current technology.

The inflation medium on the other hand imparts a consistent pressure on the valve stem from where it is trying to escape. The whole body of air is pushing on the valve core and valve cap as fluid dynamics dictate and as fluids move from a high pressure to a low pressure situation it makes logical sense to measure the pressure at the valve stem. Of course, this is how the industry has been measuring a tyres pressure since, well Mr Dunlop and Goodyear developed rubber‐impregnated cotton that formed the first pneumatic tyres.

So the question then arises how is a tyres performance measured when it is in use? It’s not possibly to attach a traditional inflation gauge to the valve stem but with the advent of microelectronics it isnow possible to attach a sensor and miniature radio transmitter to the valve stem relaying the tyre’s pressure to a monitor so that real time operating pressures can be observed.

With Nano‐technology developing rapidly, it is almost certain that tiny sensors can be manufactured to measure the temperature at different parts of a tyre. With carbon tube and piezo technology a particle that generates its own power when in motion and then transmits the data its internal sensors collect is no longer the thoughts of sci‐fi, it’s around the corner but for the moment we have to measure what we can, as we can.

Pressure is the prime metric for measuring the performance of a tyre, the consistency and accuracy of pressure to a tyres work capacity is well established. Road race teams as well as mining technicians utilise pressure as an indicator of the work a tyre has experienced. Having personally undertaken hundreds of tyre temperature tests for various manufacturers of OTR tyres I am yet to find any correlation between internal structure temperatures and surface temperatures even though the locations maybe only tens of millimetres apart. Using pressure / temperature devices that bleed air over a sensor, I am yet to find any direct correlation between the bled air temperatures to the critical temperature at the tread/belt interface.

When someone asks for tyre temperature my response is to simply ask, “Which temperature would you like?”, and then use the Tardis analogy, the complexities of the composite nature of a tyre are hidden from external gaze. On initial thought, a tyre is simple, as we industry members know a tyre is far from being a simple machine.

If we can’t save you money on your fleet operations, we’ll refund our costs at the 12 months mark,when we save your operation money we’ll accept a 25% share of those savings.

Look after your tyres and in turn, they’ll look after you, ignore them at your own peril.

Adam Gosling
TyreSafe Australia Pty Ltd
Tyresafe.com.au
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Foundation of our Societies

Monday, November 21, 2016

Every item that we consume, be it food or a material item has more than likely arrived to us via the support of tyres.
A city is dependent upon the army of vehicles to bring goods into the distribution facilities, yes granted some arrives via rail but it has been taken to and from the rail by vehicles with pneumatic tyres.

Tyres provide a reliable and dependant platform to base our modern transportation on.  Some jurisdictions are employing vehicles with multiple trailers for economy, platooning and even autonomous freight trucks are no longer something of science fiction, they’re here!

Yet all the developments are based on the foundation of the pneumatic tyre.

Tyres are being asked to do more, with less and at reduced cost.

Higher performance and reduced noise are predominant demands now.  Here’s a curved ball; electric cars may be required to have some audio device to emit warning sounds for pedestrians, what about a tyre that emits noise up to 20 km/hr then becomes progressively silent in comparison?

Then there’s the fact that tyres for most are a grudge purchase, why?  Why is it that people across many different jurisdictions all share the same complaint, “I have to pay for tyres again”?  These tyres enable the ease of movement in our societies, the transportation of goods from point of production to place of consumption, yet we begrudge paying the few cents a kilometre a tyre costs.  Some will even ignore the tyres requirements of just maintaining the appropriate inflation pressure.  Others will complain when a tyre wears in an irregular fashion but not consider the vehicle driving the tyres, “it’s the tyres fault” is an oft heard statement of grief.

Is it the duty of the rubber industry, which relies upon tyres if for nothing else but transportation of goods to educate the general public into understanding the complex role a tyre plays in our physical wellbeing, in our societies (regardless of politics or beliefs) tyres play the same role!

Tyres are truly the international ambassador of trade.  They are the same the world over, will fit the vehicles wheels in the same manner, will operate in the same manner and ask for the same respect to perform to their upmost, “please maintain the pressure at an appropriate level” is a simple request.

We place our trust in tyres to perform on our road systems, at different speeds and vastly different loads.  We trust our tyres to react whenever we steer the vehicle, accelerate or brake, our trust is total.  Did you check your tyres before you rode on them this morning?  

Why are tyres a grudge purchase? What can we as an industry do to cause a revision of this situation?  Why is it important?

As an industry providing a mobile foundation for society a lot is required, and a lot is requested.  The previous point about eco-friendly tyres, using less fuel, generating less noise, at a lower cost are all fair requests but the provision of these features requires massive R&D, which costs someone somewhere.  Why do people begrudge investing in their own safety?

Tyres, the foundation of our modern mobile society.  Invest a little time to understand how your tyres support you in everyday life, educate others to understand the critical role tyres play in our daily lives.  Generate some respect for the foundation that carries us to work and home every day, that enables us to have food on our plates.

Tyres, the forgotten factor in road safety.  When you ask for them to be there, you want them to perform to their upmost, it may mean the difference of today and tomorrow.

Look after yours and they’ll look after you!

Adam Gosling heads up TyreSafe Australia, the corporate mantra of “if your tyres are not turning they are not earning” is the basis for value adding and profit generation services provided on a global basis.
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Tyre Safety. What does it mean?

Wednesday, December 02, 2015

Tyre safety standards in Australia are being further called into question following the number of fatalities and serious injuries in the mining industry.

Not only the coroners but also the unions are pointing to a deficiency.

Australia has developed one of the few standards (AS 4457) for dealing with mining tyres anywhere in the world but injuries and deaths are still occurring.

Tyres are composite flexible pressure vessels. Unlike household gas cylinders which are rigid steel pressure vessels (like most compressed air receivers) a tyre has a load placed on it, is rolled over unkind surfaces and is generally ignored until it goes flat.

Tyres are specifically excluded from the pressure vessel standard (AS1210) with OTR tyres (>24” rim diameter) being covered under AS 4457 and any on road tyres falling under Section 25 of the Australian Design Rules (ADR).

When you stop to consider things in detail a tyre is the only connection between your vehicle and the road.

The average passenger car requires tyres to perform steering braking and some minor suspension functions as well as supporting the load (passengers and baggage). A giant mining truck tyre is required to support up to 100 tonnes, relying on the air it contains within to support that load. If there is insufficient air to support the load the tyre doesn’t complain or refuse to work like an engine or gearbox.

It just gets on with the job and literally tears itself apart performing the function we ask it to do, right up to the point where it can no longer function and fails, sometimes catastrophically. Tyres for passenger vehicles have large safety margins engineered into them during the design phase.

This is to provide a margin of safety for abuse or lack of attention but it is of course wiser to keep tyre pressure constantly monitored and the best way of doing this is to use an automatic pressure monitoring system (TPMS).

In the US, the TREAD Act mandated tyre pressure monitoring for all light passenger vehicles manufactured in that country from 2008 on.

The EU followed suite in 2012, Korea in 2013. The importance of tyre inflation pressures was mentioned by President Obama last year.

He indicated that safety on road networks is directly affected by poor tyre pressure maintenance, more fuel in consumed than is necessary thanks to tyres not being maintained correctly as well as resources being wasted.

To most people tyres are a grudge purchase. They shouldn’t be.

Tyres are what keeps us safe, keeps our vehicle on the road performs the steering and braking functions as well as ensuring comfort. It is not unusual to find that until a tyre goes flat there is little if any attention paid to it, yet the car has been washed and polished, the air freshener changed and windows cleaned.

For tyres that work hard (mining and transport) correct pressure maintenance is even more important. It is no longer adequate to check tyres when the vehicle has its periodic maintenance. Both the mining and the transport industries have for many years been monitoring engine oil pressures using gauges and electronic aids from inside the truck cab, even transmitting this data to the maintenance office so problems can be identified prior to failure.

Tyres on the other hand are still stuck in the 1950’s using a hand held gauge to check pressures, well, every so often.

So how do we tell what the tyre pressure is when we’re driving down the road? We don’t until it goes flat.

In 2015 electronic tyre pressure monitoring is not only feasible but is mandated on passenger cars. Passenger car tyres have an easy life, rarely carrying their full loads, over‐engineered and able to sustain a lot of neglect and abuse.

Compare air in a tyre to oil in an engine. If the quantity of oil in an engine is not correct then the engine will wear out faster, overheat and even destroy itself. If a tyre does not have sufficient air it too will overheat and wear out quickly.

It will also consume a lot more fuel as it overheats and then fails, sometimes unfortunately with disastrous consequences.

A tyre is not just a single piece of rubber but a composite of many different rubbers all performing a specific function.

There are steel wires within a tyre that perform other functions and all need to be operated within the manufacturers range of recommended inflation pressures. Like all mobile equipment if it is operated outside of the manufacturer’s recommended range then failure is probable if not imminent.

Whilst tyres appear simple they are a highly complex engineering feat. Adhering rubber to steel is a science all on its own, having certain types of rubber (such as tread rubbers) remaining hard enough to wear yet flexible enough to roll is another required attribute.

There are no hard and fast rules to identify issues or problems with tyres, the easiest suggestion is “if it doesn’t look right it’s probably not”.

Above all a tyre requires the correct inflation pressure. Every tyre has this same requirement.
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Ignorance of the law is no excuse, but, when the law is ignorant what is the outcome?

Monday, September 07, 2015

In Australia a vehicle can be defected having insufficient tread on a tyre, ie, it is worn below a certain level.
The thinking is sound, the tread on a tyre enables traction for braking and steering, both critical functions for a vehicle of any size.

If a tyre is not inflated correctly then it will not perform as expected, braking and steering will be compromised.

Vehicle inspectors are unable to defect a vehicle if it is operating with tyres that are not correctly inflated.
Which is less safe, a properly inflated tyre with a low tread volume or an under inflated tyre?
Vehicle designers make specific recommendations for tyre pressures.  If the tyre pressures are not as designers specify the vehicle will not perform as designed, i.e. braking distance will be increased, the vehicle will not steer as required or expected and it may experience a catastrophic tyre failure. (reference in vehicle tyre placards).

Some heavy vehicles (trucks) may undergo an approval process known as Performance Based Standards or PBS.
https://www.nhvr.gov.au/road-access/performance-based-standards/pbs-vehicle-standards

The vehicle design is simulated using computer modelling to assess the apparent safety of the vehicle.  In this simulation, precise data sets for tyres are used.  The vehicle is modelled using a specific tyre (brand, pattern and specifications cannot be varied in operations) set at a specific pressure.  If the simulation is acceptable, the vehicle is produced and can be operated on public roads.

However, there is no confirmation that whilst in operation the tyres are maintained at the inflation pressures as tested.  If the pressures vary, the vehicle will not perform as simulated.  The authorities “trust” the operators to conform.

Every tyre manufacturer has charts and graphs on how tyre inflation affects tyre wear and fuel consumption, well-accepted facts.  Even President Obama commented in 2014 on the importance to public safety and the economy for setting tyre pressures correctly.

Australia does not recognise under inflated tyres as a safety critical issue.  Other jurisdictions such as the USA, the EU, Korea, even China recognise underinflated tyres as an important factor in road safety and the economics of vehicle operations.

Tyres are the sole connector between the vehicle and the pavement, the critical safety item that determines braking and steering.  Why do Australian vehicle regulations ignore tyre inflation?

Why do safety bureaucrats turn to solutions ever increasing in complexity and expense ignoring the most basic of all safety systems on a modern motor vehicle, the tyres?  KISS!

Why is Australia so laggard when it comes to tyre safety?  New Zealand has had a tyre safety month for 8 years.

Why is Australian law so lacking in this area?  The law, or lack thereof, is an ass I contend.
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Loss Reduction not Cost Reduction.

Monday, September 07, 2015

Much capital is wasted in procurement chasing lowest cost options. Procurement gain most of their kudos and KPI’s through buying at reduced costs, however cost reduction invariably ends up with increased losses. This seems counter intuitive but consider that most procurement departments know little if anything of actual operations. A holistic view must be engaged if loss reductions are achieved.

A premium tyre may not always provide a lower cost per kilometre outcome but performance can never be judged on purchase price alone. Can your fleet managers put hand on heart saying, “my tyres cost me X cents per kilometre to operate” with facts supporting this statement?

Scientific studies have shown that low cost tyres often have increased rolling resistance. This is a result of the design and construction of the low cost tyre, there is a reason they are low cost. R&D is never cheap. Sure, there was a little money saved in the tyre’s purchase price and while procurement achieved their KPI’s the fleet’s fuel bills increased, tyre service costs increased, availability fell as tyres failed prematurely and the operations department costs increased.

Who cares about tyres? For most transport operations, tyres are usually the next cost to fuel. If a company was to receive only 750 ml of fuel for every litre paid for the board would be in uproar, yet willingly accept tyres only yielding 75% expected life, this seems to go unnoticed.

Companies have HR departments managing the requirements and expectations of the workforce, highly skilled knowledgeable personnel improving the mechanical maintenance of the equipment. Tyres, on the other hand, are often outsourced to suppliers (whose aim is to sell tyres) or shoved forgotten down the back corner. When a tyre management plan is suggested, scorn is the usual response

A tyre relates it’s life to a trained observer. The standard of vehicle maintenance as well as driver habits are exhibited freely on show. Note, “trained observer”, a passionate practitioner armed with knowledge and experience. Isn’t this the same requirement as HR & mechanical maintenance?

The first requirement of a tyre for successful operation is inflation pressure, its common knowledge that a flat tyre doesn’t go far, few seem to realise a properly inflated tyre provides long service and the expected level of safety? Without adequate pressure maintenance tyres will not provide the expected performance.

Some companies suggest that all tyres are checked before the vehicle leaves for a journey that may not see the vehicle return until the next periodic maintenance service is scheduled. How are the tyres checked during the interim? Traditionally the driver will thump the tyres during rest breaks, verifying that the tyres are not flat or grossly under inflated.

How are tyres checked during the 3 – 5 hours on the move? Unless there is a tyre pressure monitoring system fitted, they’re not! Tyres do not all react in the same manner. Detailed logs of operating tyre pressures have shown that tyres in different positions on the vehicle react in different ways. One of a dual pair may be hot, an axle group may be hotter because the alignment is out of spec, a dual pair may be hotter as the wheel bearings are on the way out or a brake is dragging.

Dual tyres usually do not operate at the same pressure, this is why they are derated by the tyre and rim associations, however cold pressures are usually set to the same level. Why? Because it’s easier that way, we prefer to throw money away because it’s easier.

Understanding what tyres are experiencing in real time is the fundamental key to loss reduction. If you can’t measure it, you can’t improve it. You can’t measure tyre pressure by thumping the tyre with a bar.

Using real time pressure monitoring you can understand how your tyres are actually performing. A loss reduction strategy involving tyre pressure monitoring can provide substantial gains in just tyre performance, without mentioning fuel, rotating equipment life even driver fatigue.

Tyre companies publish volumes of data on how under inflation affects tyre life and fuel consumption. Many fleets study driver habits in order to reduce fuel consumption yet for a fleet with poorly maintained tyres there is a potential 5% savings in fuel alone that can be made. ECU data is reviewed and filtered, driver scorecards raised but no one has considered tyres.

The kudos gained by procurement for purchasing a low cost item may return with a venomous bite. If operating costs increase it could be the few percentage point difference between a profit and loss, in safety terms it may well be the survival of your employees as well as your business and reputation.

What is your loss reduction strategy? The lowest hanging fruit is managing tyre pressures. It’s ripe for picking in the majority of transport operations. Will you continue to ignore this opportunity to reduce your losses?
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Tyres are NOT just consumables. They are a high value asset.

Monday, July 06, 2015

Tyres form a highly ranked cost centre in a mining or transport operation, quite often being second only to fuel.

In the life of a trucks engine, tyres will cost more money than the engine costs to rebuild.

Tyres are an investment in making a profit, without tyres the truck does not move.

If tyres fail when a truck is in operation, the outcomes can be very expensive, from a safety perspective to then repairing the resultant damage.

So why does management generally ignore the investment made in tyres? So why is tyre maintenance relegated to once a week if we get to it?

Tyres work so well just soaking up the abuse that’s dealt out to them without complaint or protest. If we treated our engines the same way we treat tyres they would expire well before they should do and everyone would be complaining!

It is startling to hear management speak of cost cutting and economics yet continue to ignore their second largest cost centre, TYRES!

A tyre running at 10% less than its ideal pressure wears out 12% faster than it should do. It consumes 2 – 3% more fuel than it should do due to increased rolling resistance.

A difference of ONLY 5 psi between dual tyres decreases wheel‐bearing life by 10%

A difference of only 5 psi between duals means one tread wears faster, the casing on the other tyre fatigues faster, overall effect is a large life reduction.

Differences in tyre pressures across axles impose additional loadings on drivelines, from wheel ends back through differentials to transmissions, reducing life and increasing costs.

Tyres are messengers, they tell of the vehicle condition and maintenance philosophies. A worn out shock absorber will show up on a tyre, misalignment shows up on a tyre, maladjusted brakes show up on tyres, a trailer dog tracking will show up on steer tyres.

Simply put tyre rely upon the correct pressures to perform as designed, for a truck to brake within the distance the vehicle designers intended, to steer as designed and to put the power to the ground as the vehicle designers intended tyre pressures must be correct. If tyres are not maintained correctly then costs escalate, without anyone actually realising. No ABS or ESC can compensate for poor tyre pressure maintenance!

How many maintenance managers can tell you how many cents per unit distance their tyres cost to operate? They can tell you all about the fuel and how this truck and this driver are XYZ... but then don’t know about their next largest cost centre, those round black things called tyres that no one wants to know about?

I presented a statement about tyres to a major distribution company that prides itself on knowing how their buildings operate down to the last light globe. The board members jaw collectively hit the table when they realised the fact they had over 4000 assets worth in excess of $3,500,000 that they had no idea about, no control over and did not know how much they cost to operate.

These assets directly affect the safety of their operations, directly affect their bottom line and they had no control or knowledge about these assets. The danger for damage to their reputation was immediately realised with no tracking of tyre assets undertaken no evidence was available to demonstrate diligence in maintenance.

Using real time monitoring tyre pressures are easily maintained. Hot operating pressures are different from cold pressures. A well‐maintained tier 4 emission‐controlled truck showed a difference of more than 5 psi between dual drive tyres on both drive axles in operation. The cold pressures were set accurately but in operation, the pressure varied considerably. The result, decreased tyre life, decreased tyre performance in traction both under drive and braking, increased fuel consumption. With data collected from real time tyre pressure monitoring changes were made to achieve even operating pressures. Costs decreased, profits increased.

How do you know what your operating pressures are? Without real time monitoring you actually have no idea, weekly pressure checks tell you nothing, they do put money into the pocket of your tyre service provider, money for jam.

Why does management ignore their second largest ongoing investment? I can only conclude they are making too much money to worry about it. Sounds like a recipe for disaster to me. “No Your Honour I cannot demonstrate that we have maintained the tyres on our fleet appropriately and safely” is an over whelming situation to be put in. How would you deal with that situation?

How do you maintain your tyres? With a hope and a pray, once a week? Real time pressure monitoring provides positive economic return on investment, provides safety outcomes that cannot be valued, it is simple and effective.

Look after your tyres in real time and they will continue to look after you, safely and economically.
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Benefits Gained from Using TPMS

Saturday, April 11, 2015

I am always surprised when speaking with people about the benefits of using tyre pressure monitoring systems (TPMS). It seems that many people don’t consider the costs of operating tyres on commercial fleets and there are probably more who don’t consider their own safety as being a thing to value.

One fleet operator was down on using TPMS. His freight was children, a school bus operator. He was transporting everyone’s most valuable asset, their children. He arrived at the depot in his car, which was fitted with TPMS yet he was more than happy to send his precious cargo out on buses without any way of knowing if a tyre was deflating. Not only was he jeopardising the safety of his charges but also he was costing the operation a bucket of money. How so many ask?

When a tyre is rolling down the road, it consumes energy. On a vehicle this energy is provided by the fuel. The degree of resistance to rolling is caused by many factors, the design of the tread pattern, the casing of structural members of the tyre, the road surface itself and the largest factor of them all is the inflation pressure of the tyre. Remember getting your pushbike home when it had a flat tyre? It was a lot of work wasn’t it? The road surface hadn’t changed only the inflation pressure of the tyre.

When a tyre supports a load on a vehicle it deforms under load. There is a technical term known as hysteresis, this explains the way a block of rubber is deformed and the energy it consumes. The higher the load the higher the deformation, it’s that simple. With an increase in vehicle speed comes an increase in the frequency of the deformation but there is a catch. The faster the vehicle travels the greater the deformation caused by the load. A small bump in the road at slow speed can be a large bump at high speed. So the energy consumption due to hysteresis is exponential. A technical way of saying the faster we go the more energy we consume, a lot more than we would travelling slowly.

Using TPMS we observe the pressure increase in a tyre in operation. A tyre moving about the suburbs travelling slowly, not carrying a lot of load barely increases in pressure. The same vehicle travelling at highway speed shows, with properly inflated tyres, we observe an increase of up to 15% over the cold setting. Put some load into the vehicle and suddenly the tyres are over working, the operating pressures are heading north of 15% indicating the tyre is over working.

A tyre supports the load imposed on it with the air contained inside. The higher the load the more air required. Remember the hysteresis? The faster the vehicle travels equals the more air the tyre requires, so when you’re driving around the city with a light load your tyres aren’t working. As soon as you add more load and start going faster your tyres require more air to support the load and the speed.

Using a TPMS unit a commercial driver can tell when the tyres are over working, just the same as someone who hooks up a caravan for a holiday onto the car they normally use around town can.

A tyre is formed using a process called vulcanisation. This is a one‐way process that combines chemicals and raw rubber to form what we know as a tyre. This is a one‐way process, it’s not like freezing water where when it defrosts it turns to water again. Making a tyre is like baking a cake, when it’s made that’s it. It can’t be unmade.

When a tyre reacts to work via hysteresis it generates heat. It generates a lot more heat than just sitting in the sun, you can’t tell how hot a tyre is by feeling it generally. The heat is inside the tyre structure. By the time you can smell it and think “gees that tyre is hot” the damage is done, the cake is burnt. By this time the inflation pressure will have increased probably well beyond 25% above the cold pressure, far too much. Tyre manufacturers suggest that for road use pressures should be in the 10% ‐ 15% range. Any higher than that the tyre is over working. In specialist tyres like motorsport and the giant haul truck tyres the pressures do go higher but those tyres are working a lot harder than normal road tyres.

Using a quality TPMS you should be able to set the over pressure alert level. I prefer to set mine at 19% above cold, yes there are times when I work the tyres hard, I throw 160 kgs of chook food in the back of the ute and I know this is worth 2 – 3 psi on the run home. If I get an alert I know the tyres are already in danger of overheating. The easiest way to cool the tyres is to slow down, remember that exponential increase? It works the same in reverse too, just 10 km/hr will make a lot of difference to the work a tyre does at highway speed.

Under pressure is where damage is done quickly. If I ask you to carry a heavy load you can walk well enough, but if I ask you to start running then you will perish quickly, a tyre is no different. So how does this all relate to the school bus operator?

By not understanding how his tyres are performing he is not only using a lot more fuel (remember pushing the bike home?) but he is wearing his tyres out a lot faster, there is a double loss which compounds. He has to change his tyres more often, can’t sell the casing or use them for retreading but worst of all he is endangering his cargo.

If a tyre is underinflated and it fails catastrophically, (yes like the road gators you see on the roadside) then there is a potential loss of control that could result in, well, lots of parents worried about the safety of their children. Not a place I ever want to go.

“But that won’t happen to me” is the standard statement, oh I see so you can tell what your tyres are doing when you’re travelling down the highway with the caravan hooked up behind can you? Can the truckie can see what the inside tyres on his trailers are doing in his mirrors when travelling at 100 km/hr?

Use a high quality TPMS, your tyres depend on you to take care of them so they can take care of you. When you consider there is a small patch of rubber about the size of your hand that is responsible for your safety why wouldn’t you want to look after it the best you can?

Adam Gosling heads up TyreSafe Australia; providing management and tyre safety guidance to private operators as well as fleet owners across Australia helping them to maximise safety and increase their return on the investment made in their tyres. Tyres are not a grudge purchase they keep you safe!
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