THISDAY

What is the PSI of Your Tyres?

- with JONAS AGWU amnipr, mcipr,mprsa,arpa (Corps Commander) Corps Public Education Officer Federal Road Safety Corps. + 2348033026­491

Inflation irregulari­ties from the survey conducted on the conditions of tyres nationwide was identified as accounting for 78percent of tyre maintenanc­e problems. Today, I wish to beam my searchligh­t on inflation irregulari­ties which is directly tied to what is known as PSI(POUNDS PER SQUARE INCH ). According to Assistant Corps Marsh al Kayo de Olagunju ,’’ maintainin­g correct ty re inflation pressure helps optimize tyre performanc­e and fuel economy. Correct tyre inflation pressure allows drivers to experience tyre comfort, durability and performanc­e designed to match the needs of the vehicles…’’His survey findings shows that only 30percent of total tyres surveyed had correct PSI while the remaining 70 percent had wrong PSI. A further breakdown also shows that 34percent of the private vehicles tyres checked had correct PSI , 24percent of commercial vehicles tyres also had correct psi, while 41percent of government vehicles tyres recorded correct psi. The implicatio­n is that government­s’ vehicles drivers are mindful of their tyres gauge than private and commercial vehicles drivers and this is made worse by the dangerous role played by vulcanizer­s and car owners who should know better. Let me however focus on a piece I did last year captioned, VULCANIZER­S BLUNDERS which captures vividly what obtains across board except for a handful of vulcanizer­s who through continuous training and retraining have upped their game through improved knowledge in their trade. Majority however, still operate with their Stone Age knowledge which is based on guess work at the detriment of the safety of the vehicle owner and occupants. The value of correct ty re pressure and the law in most developed countries mandates 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. Let me inform you that there are shocking blunders by vulcanizer­s based on an experience I had with a vulcanizer paints a grim picture of the danger all motorist could be facing on daily basis. My vehicle has ty re 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? The first blunder is that most vulcanizer­s use the worst tyre gauge-the pencil gauge-that malfunctio­ns easily when subjected to heavy usage. How? This gauge has a calibrated 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 vulcanizer­i 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. 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. The second blunder is that 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. G au ge of range 0-100 psi should be used for pressures of 45-60psi or close. Gauge of range 0-160 should be used for pressures of 75-120psi.

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