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As an added value feature to our first BrakeWatch project held in November 2005, we decided to add on a TyreWatch component to our project and found a willing and able partner in Bridgestone South Africa. The Bridgestone team not only provided training on tyres for the cops on the day prior to the hands-on exercise, but also sent a full compliment of qualified and enthusiastic staff to the test centre in Middelburg on the day. This team operated under the experienced and beady eye of Marcus Haw, technical manager of Bridgestone. What they found in terms of tyre faults leaves the mind boggled - as the following photographs with comment from Haw demonstrates.
 

This tyre has been badly cut or damaged. The area of the damage is at a particularly sensitive part of the tyre for two reasons: One, the body ply turns up around the bead at this point and two; the area is a transition point from a rigid area (the bead) to a flex area (the lower sidewall). Because of the damage, the area is severely weakened allowing more flexing to take place than was intended in the structural design. Each time this tyre rotates and this area flexes with ground contact, the tear will grow and the body ply turn-up will start pulling loose. At some point in the near future, the body ply will pull away from the bead completely resulting in sudden and complete air loss (a lower sidewall blow out). A tyre in this condition should be immediately deflated and removed - in that order.

The traffic officer is pointing to a totally smooth - and totally illegal - tyre. There are two concerns here: One is that the tyre obviously has no grip left. In the dry, this is maybe not a problem but in the wet, it is highly dangerous - and although fitted on a dual position, it still performs 50% of the grip at this end of the axle which people seem to forget. Secondly its diameter is now significantly different from its mate so it will accelerate its wear rate rapidly exposing its under-tread and belts, as well as transferring part of its carrying function to the larger tyre, thereby increasing that tyre's wear rate and decreasing the casing life through aggravated heat build-up. In this photo, one can also see that the outer tyre on the front axle is totally flat due to a large sidewall impact, pointed out by the officer in pic 3. So half the total carrying capacity of the tyres on the one side of the vehicle is gone. The most likely result of this situation is that the truck will never reach its destination because overstress of the inner tyres will cause them to blow.

	This close-up of the tyre referred to in picture 2 shows how the beads have deseated from the rim flange due to the total deflation of the tyre.
	The Bridgestone team points out a valve problem. The problem here, shown in pic 5 is that the valve stem is in contact with the brake drum. Brake drums get extremely hot and this heat is transmitted through the valve stem to the valve core, which is simply a very small non-return valve activated by a small spring. The tension in this little spring is lost through excessive heat from the brake drum and you have a leaking valve. In this case the danger was lessoned somewhat because a decent steel valve cap had been fitted, with a rubber cover. If, as is often the case, no valve cap is fitted, or a plastic valve cap is used, the tyre slowly deflates, overheats and the tube blows. Note that this is on a steer wheel so the blow-out has the potential to cause loss of control. All this because no-one bothered to check the clearance and bend the valve stem into a correct position. It is, in fact, a myth that a blow-out automatically results in an accident and it has been proven in controlled tests overseas that it is the driver's reaction which is the actual cause. However, proper advanced heavy vehicle driver training is sorely lacking in my beloved Africa and it is very often the case that a front wheel blow-out - because of stupid negligence - results in death. Life is still number one on my list of priorities but sadly it does not appear to be so with many heavy vehicle operators. In Picture 3, one can see how easy it is to avoid all the above by bending the valve stem to give some clearance.

These show different areas of the same tyre, also fitted to the front wheel. The casing of the tyre is severely degraded through age - and has been recently retreaded judging by the tread depth. The retreader in this case should be shot, or at the very least arrested for attempted murder. Then his business should be closed down and he should be refused a licence to ever operate a business more safety orientated than the manufacture of brooms. The shoulder damage on this tyre is due to the weakness in the casing. It is most probably due to curbing but had the casing been of sufficient strength, it could maybe have withstood the stress. Retreads should not be fitted to front wheels but this tyre should never have been retreaded in the first place. Retreading is a fine industry with generally good codes of practice and this should not be taken as an example of the industry in general but should be taken as a very serious warning of what may be happening in certain cases.

Here again we see a severely degraded, over-aged and damaged casing. The tyre is not roadworthy and should be scrapped immediately. Notice how the body cords are exposed in the middle of the sidewall. A broken cord reduces the strength significantly.

In this case, the emphasis is on general wheel maintenance. Missing wheel studs and in this case also wheel bearing cap nuts and studs are an immediate indication of a transporter who has no pride, responsibility or understanding of general safety practice and should probably not be licensed to run any vehicles other than wheelbarrows. It is generally known that unequal torqueing of wheel nuts results in uneven stress in the wheel rim which can - and usually does - cause irregular wear in the tyres. Now consider the stress that totally missing wheel nuts place on a rim and the possible consequences to both rim and tyre.

Here again, out of eight wheel studs, four have actually got nuts on them. Half a tightened wheel relates to half a brain in the owner of this vehicle. Is safety not a consideration?

Again shows a retread fitted to a front wheel and a new retread on a suspect casing. Is it only in this area that this is happening, or should we be worried about wider unethical conduct? This is extremely serious and needs to be investigated urgently. I would be very interested to get comment from the general retreading community for whom I have a lot of respect and have worked closely with over the years.

Picture 13 is a close-up of the tyre which shows that it should never have been considered for retreading. Note also the poor splice on the tread surface.

Here again, out of eight wheel studs, four have actually got nuts on them. Half a tightened wheel relates to half a brain in the owner of this vehicle. Is safety not a consideration?

The photo shows quite clearly that the front axle is running in a different plane to the rear. This will result in accelerated wear on all eight tyres fitted to this bogey as well as excessive stress wear on most of the suspension components (which are actually probably all worn out and are the reason for this situation). Here again we have an unroadworthy vehicle and 'unroadworthy', very simply, means it should not have been on the road.

With these two tyres, the same situation exists as was referred to in Pictures 7 and 8 and in fact, probably also refers to the same retreader. Notice again the condition of the casings, especially the inner one. It is no less than criminal to run vehicles on these tyres but again, they have been recently retreaded. Retreaders, as mentioned, have a strict code of conduct and a thorough inspection process.  Obviously that does not happen at this retreader and while it may be criminal to run tyres like this, the fact that someone is retreading them is beyond belief. Public hanging should possibly be brought back for people like this.

Broken bolts on suspension components will usually induce accelerated wear in other areas. While this particular photo doesn't show a situation where the broken bolts are directly related to the smooth tyre seen, it again shows the lack of pride and responsibility in our local transport industry. The tyre is at minimal legal depth but should have been already removed and replaced from a safety point of view and in the interests of cost saving.

Here we see a perfect example of a total mismatch in dual fitment. Not only are the tyres of a different size but they are also of a different tread pattern. The results of this type of fitment are accelerated and irregular tread wear, and accelerated and unnecessary stress and aging of the tyre casings - and of course, added and unnecessary expense to the idiot who allows a unit like this to leave his yard.

	What you see here is a wear mark left by a tyre coming into contact with the chassis. Do we need to point out the problems here? Obviously we do otherwise we would not be seeing it. Tyres should not, ever, come into contact with bits of the vehicle they are fitted to. If a tyre has caused this type of wear to the steel chassis, ponder for a moment what the steel chassis has done to the rubber tyre. Pic 19 shows the same wear part on the chassis. Notice the distance between the tyre and this part of the chassis. This was on a tipper and the rubbing was obviously happening during tipping. In picture 20, we see the same tipper with the same sort of wear on a different part of the chassis. This is on the lower part of the chassis, at the front axle. Imagine the load that would drop the chassis to the point where it comes into contact with this tyre. But, bear in mind also that everything on this vehicle must have been modified, repaired, replaced or otherwise changed during its life. If not, the mathematical ability of the original manufacturer/designer must come under serious question. Again, an unroadworthy vehicle which is doing continuous damage to the tyres and should not be on the road.

Apart from the missing wheel bearing cap nuts and studs indicating once again that this vehicle belongs to a transporter who takes no pride in his work, this picture also shows that it is highly unlikely - most probably impossible - to check the pressure or inflate the tyre fitted to this abused and neglected wheel. An incorrect length valve stem has been fitted, the end of which is now jammed up against the rim. The whole picture again is one of negligence, no maintenance and not caring.

Wheel rims and the width of wheel rims used for certain size tyres are specified so that there is sufficient distance between the dual tyres to allow the normal flexing of the sidewalls of the tyres to occur without touching each other when the footprint comes into contact with the road. A further function of the dual spacing is to allow cooling to take place between the dual tyres. In this case, the dual spacing is almost non-existent and therefore the tyres will constantly be touching, as can be seen at the bottom part of the tyres. The friction this causes will significantly accelerate the heat build-up in the sidewalls of these tyres which, considering that the cooling function has been eliminated, is at best going to shorten the overall life expectancy of the tyres and at worst, could actually wear through the sidewalls resulting in two destroyed tyres. While the dual spacing is the most important consideration in this particular case, notice again the mismatching of the tread patters. Picture 23 shows the duals on the opposite side of the same axle. While the mismatching is equally dismaying, the dual spacing is much better.

Spot the problem. Refer to earlier descriptions of problems related to smooth tyres and the dimensional differences.

Here we have an almost smooth tyre matched with one that has been taken beyond smooth, exposing the under-tread and almost through to the plies. Unroadworthy, illegal, unsafe, possibly very exciting in wet braking. Again hang the owner. What can one say?

A different example of poor retreading. In this case the casing appears to be acceptable but the buffing - most likely the buffing radius and definitely the tread width used - are not up to standard. It's not a safety related problem in this case but will cause accelerated and uneven tread wear and therefore unnecessary expense. Here again, one must look at two considerations. Obviously the first one is whether the recapper has any idea of what he's doing. In this case, I reckon not. The second is directed at the transporter where we have to ask: If you have any pride in your vehicles, would you fit this? So again the transporter's general maintenance standards come into question. And if maintenance is a problem, the next problem automatically becomes safety.

Should we keep showing these? After all, I'm sure that by now mismatching and smooth tyres are becoming boring? But then again, if we keep on showing the same problem maybe - just maybe - someone will catch on that this is illegal and unroadworthy.

The team from Bridgestone which worked tirelessly to identify the tyre faults shown in this report. From left: Bester Betha, field engineer; Marcus Haw, manager field engineering; Wayne Mostert, field engineer; Andrew Smale, training officer; Stephen Norris, field engineer and Romano Daniels - GM, group public relations.

One picture, three problems! Can you spot them? Problem 1: Valve stem end to inner wheel positioning suggests it is highly unlikely that pressure maintenance is taking place here. Problem 2: Bearing cap studs missing. Problem 3: If you take careful notice of the hand-hole matching, it would suggest that the inner valve is stuck somewhere behind the rim, which would make pressure maintenance on the inner wheel impossible.

Misalignment of the hand-holes of inner and outer rims is a common concern and results in the pressure maintenance of many inner tyres being neglected. This is a good example of the misalignment of hand-holes although, in this case, with effort, one could access the inner valve. However, in the transport industry it is commonly known that time constraints as well as other considerations such as lack of care, seldom result in the effort required being applied.

The inside tyre here has a huge separation taking place between components; most likely starting at the body ply turn-up around the bead and most likely caused through huge deflection (impact). The tyre should have been removed immediately since total failure is imminent. However, one must be realistic and with my general criticism of maintenance, it is understandable here that with the positioning of the separation, it can be missed during cursory checks. The point is though, regular thorough checks should be the norm, and unfortunately normal checks are normally more cursory.

The valve has two problems. One is that it is missing a valve cap which allows dirt and contaminants into the valve core which, in turn, allows the possibility of causing the valve core to get stuck open causing air to leak. The other problem is in the placement of the valve or the length of the valve stem used. While not impossible because of the space between the inner wheel rim and the end of the valve stem, it was found to be very difficult to get a pressure gauge onto the valve. This usually results in pressure checks being neglected with the consequences normally associated with lack of pressure maintenance. Just for interest sake, notice also the area around the wheel nuts. This shows that either previous or current movement of the rim has occurred.

Loose and missing wheel nuts and broken studs again. Notice also that the one nut (adjacent to the broken wheel stud) is of a different size to the others and has been tightened into (almost right through) the stud hole. What does this tell one about the maintenance standards here?

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