SAB UCHEAGWU is a friend,a brother and a colleague whose contributions have richly improved my knowledge on tyre care and the challenges it poses to road safety management in our country. Since our paths crossed some years back, he has been a mentor I will never forget in a hurry. A good number of the materials I share with you are courtesy of SAB. Today, as I continue our look on driving risk behavior, I wish to share this rich material from him on tyre blowout as a follow up to last week’s focus hoping that travelers will get needed safety information preparatory to the December rush.
Tyre blowouts are among the major causes of fatal accidents that has claimed the lives of different categories of motorists and as we gradually await this year’s Christmas celebrations usually characterized by increased irresponsible driving, many more may still die due to tyre blowout. That is why this focus should be of serious concern for motorists planning to travel this season and even beyond this coming festive season. This piece will raise awareness on the major but preventable causes of tyre blowouts and how they can be prevented.
 Let us briefly look at the major causes of tyre blowouts which most people are not aware of and so are very negligent about. The major cause of tyre blowout is incorrect tyre inflation, especially under-inflation. Under-inflation causes two things that lead to tyre blowouts; It causes undue flexing of the tyes as the vehicles speeds along the undulating surface of the road. This causes a separation between the internal materials used in making the tyre and the rubber flesh that holds the materials. This separation weakens the tyre.It also causes an increase in what is known as ROLLING RESISTANCE (RR) as the vehicle moves. The increased RR generates a tremendous amount of heat. This heat, together with the separation of the internal materials of the tyre as stated above, leads to an explosion or blowout.
Incorrect tyre inflation could also cause accidents in other ways. When a tyre is incorrectly inflated (over inflation or under-inflation), it makes a partial contact with the road surface and so does not have a firm grip on the surface. With overinflation, the edges of the contact patch (the part of the tyre that should be in contact with the road surface) do not touch the ground. While with under-inflation, the crown (the middle portion of the tyre) of the contact patch does not touch the ground. So either way, you have an impartial contact of the tyre on the road surface and so less grip.
This impartial contact could cause accidents in various ways:Since the tyres don’t have a firm grip on the road surface, it prolongs the stopping distance when the brakes are applied in an emergency and this could make the vehicle crash into the object it wants to avoid. It could also lead to loss of control of the vehicle when speeding. This is more with over-inflated tyres.High vehicles like trailers, tankers, etc could lose their balance when they hit a bump, pot hole, or whi;e descending a sharp bend. The situation can be likened to someone with one leg shorter than the other- over-inflation representing the longer leg while under-inflation, the shorter leg. When given a push, such a person can easily loose balance. No wonder these vehicles fall and loose brakes easily when subjected to abnormal road conditions like bumps, potholes and bends.
My friend SAB conducted a study at Orile Tanker park few years back and the study revealed some shocking results. Observations at the tanker park, Orile showed that most of these vehicles have a combination of over-inflated and under-inflated tyres. To our greatest surprise, most of those with under-inflation were deliberate. According the drivers, those tyres were weak and if properly inflated, they could burst. This is another dangerous ignorance at work. Using weak tyres is enough bad news. Under-inflating them makes matters worse. Under-inflation, as explained above, will actually accelerate their likelihood of bursting. In fact, if you trace the causes of most accidents, you may discover that incorrect tyre inflation is directly or indirectly implicated. It is important to note that a tyre that is correctly inflated will handle bad roads, speed and other road conditions far better than one that is not correctly inflated. These will result in drastic reduction in road accidents. Correct tyre pressure is such a vital issue in reduction of road accident that America, as well as some other developed countries, made it law that all vehicles manufactured from 2008 must be equipped with AUTOMATIC TYRE PRESSURE MONITORING SYSTEM (ATPMS). This device monitors tyre pressure situation every second and alerts the driver through a monitor on the dashboard about any tyre that has incorrect pressure in it so that the driver will take action before it is too late.
The second shock was the blunder prevalent among vulcanizers. An experience he had with a vulcanizer paints a grim picture of the danger all motorist could be facing on daily basis. ‘’My vehicle has tyre pressure specification of 35 psi by the manufacturer. One day, I drove into a vulcanizers shop to pump up one of my tyres. After pumping, the vulcanizer got 35psi reading on his pencil tyre gauge. I checked with my dial tyre gauge to confirm his reading and got a whooping 60 psi. I asked him to check again with his own gauge’’. Again he got 35 psi while mine still read 60 psi. Why the huge differences in reading? Who was right?
There was yet a third blunder among vulcanizers- Most vulcanizers use the worst tyre gauge-the pencil gauge-that malfunctions easily when subjected to heavy usage. How? These gauge has a caliberated piston that is pushed by air that comes out from the tyre when connected to the valve stem. The extent to which the piston is pushed depends on the pressure in the tyre. The higher the pressure, the farther the piston will be pushed and the higher the reading. On fortunately, with heavy usage (as in everyday application by the vulcanizers), the hole through which air passes to activate the piston can be constricted by dust coming out from unprotected valve stem of the tyre and also by the rust due to moisture from the damp air coming out from the tyre.
With the air passage so narrowed, the amount of air passing through it no more corresponds to the air pressure in the tyre and so a faulty reading results. Worse still, when this happens, there is no way the user will know. It will still be giving reading but highly incorrect readings. That was the case with vulcanizer I had the encounter with. After I explained to him why his gauge was the one at fault, he did not agree saying he had been using the gauge for long and never had any problems with it. Because of the seriousness of the issue, I had to prove to him conclusively that he was wrong and endangering the lives of innocent road users.Â
We had to get a brand new pencil gauge that has not been compromised by dust and rust. When it was used to gauge my tyre, the reading corresponded exactly to what I got with my gauge. He had no more argument and willingly complied with my demand to submit the dangerous gauge to me because I insisted that he must not use it again. This type of gauge is also affected by temperature, humidity and altitude. So the readings got at different locations and weather conditions could differ substantially. Not only that, most vulcanizers use this type of gauge, they use it on daily basis and for years. The one used by the vulcanizer mentioned above had signs of abuse and over use all over it. It is the same story North, East, West, and South.
But why do the vulcanizers use this type of gauge? Essentially because it is the cheapest gauge in the market. Not only that the vulcanizers use the pencil type of gauge, the use one gauge for all tyre pressure. Using one gauge for all pressure measurements is a blunder. Why? Every gauge has a calibration range designed for a certain pressure group and will only be accurate when used for such pressure group. Gauges are accurate when used to measure pressures whose values fall within the middle range of the gauge. For instance, if you have a gauge with range 0-60psi, the middle range is 30psi. this gauge will accurate for pressures whose values fall around 30psi. so pressures that should be measured with this gauge should be about 25-35psi. Gauge of range 0-100psi should be used for pressures of 45-60psi or close. Gauge of range 0-160 should be used for pressures of 75-120psi. So if one uses a gauge not designed for a particular pressure group, one will get incorrect and misleading reading.
Unfortunately, the vulcanizers are innocently ignorant of this. Most of them use 0-160psi or 0-120psi gauges for all their tyre pressures, thinking that a wide ranged gauge should accommodate all the tyre pressures they measure. This sounds logical but grossly wrong and very dangerous.
You can imagine the combine effects of Blunders 1 and 2 discussed above. So, while you drive into the vulcanizers shop to fix ones tyre pressure problem, the vulcanizer inadvertently sets one up for the very problem one has gone to fix. The result is that almost all the vehicles that ply our roads have their tyres incorrectly inflated. Just run a random check and you will confirm this. What a time bomb these vehicles could be. You can imagine what could have happened if had driven away with 60psi pressure in a tyre designed for 35psi. Yet this is the fate that all motorists face every day. How many people have a personal gauge confirm what the vulcanizer pumps into their tyres?
Since lives are involved, reliable tyre gauge cannot be compromised. The correctness of the tyre pressure is as good as the gauge used to measure it. So it is of vital importance that tyres are accurately gauged and pumped. This therefore emphasizes the urgent need for the vulcanizers to use accurate and reliable tyre gauges that should also have a way of telling when they malfunction otherwise one will be getting readings without being aware of it and that could mean disaster.
A reliable gauge is one that has a fully geared precision movement parts and with bourdon tube. Unlike the piston-plunger-type gauges (the pencil type), the bourdon tube movement is not affected by changes in temperature, humidity or altitude and so will give correct reading anywhere and anytime. When it malfunctions, the needle on the dial will indicate by erratic movement when engaged to gauge tyre pressure. A sample of this gauge has been presented to the vulcanizers and fortunately, they are willing to use it. A vulcanizer should also have at least two gauges of different ranges (0-60psi and 0-100psi) as explained above.
