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Tread carefully on re care

18th March 1977, Page 39
18th March 1977
Page 39
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Page 39, 18th March 1977 — Tread carefully on re care
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Which of the following most accurately describes the problem?

THE COST of tyres has reached such a peak that it makes good sense to look after them and thus increase their effective lifespan. Many operators fail to appreciate just how much tyre life is shortened by poor maintenance.

I visited Ralph Wilde, fleet technical sales manager of Dunlop Tyres, to discover what precautions should be taken to extend tyre. life.

In Mr Wilde's view, when it comes to tyres, some operators are their own worst enemies. They squeeze their tyre distributor in two ways, by insisting on more and more discount while expecting immediate service.

Truck tyres

Truck tyres are, he says, so reliable these days that they are taken for granted. Some fleet operators don't even have a compressor to re-inflate them when they loose pressure, prefering to drive the vehicle on soft tyres to the nearest air point! Invariably the truck is fully laden, causing immense damage to the side-walls and overheating both tyre and tube.

Dunlop's advice to these operators is to make sure they have a suitably efficient compressor capable of providing enough air to inflate the tyre.

Modern truck tyres need to be blown up to around 690kN/sq m (100psi) so its no good having a compressor which can only reach 550kN /sq m (80psi). This may seem obvious but, Dunlop says, there are plenty who don't realise it.

From the outset it's important to choose the correct tyre for the work to be done.

Cross-ply tyres, which usually have a kerbing rib, are particularly suitable for urban delivery work where the maximum speed is low and journeys are short. For long-distance work at high speeds on A-roads or motorways radial tyres are the order of the day. Radials give longer life and their light-weight construction helps keep the temperature down. , However, they run the risk of possible side-wall damage as the walls are of thinner construction and therefore more vulnerable.Radials also have the advantage of improving fuel consumption with their low rolling resistance.

Inspections

Having chosen the right type of tyre the next most important thing is to keep accurate records. These will help to confirm the choice of tyre and ensure that uneven or excess wear are spotted in time, so that corrective action can be taken.

A simple daily check on pressures and tread depths can pay handsome dividends. Regular rotation will even Lir/ the wear, again to improve tyre life.

If there are signs of the front tyres shouldering or scuffing, the track is the first thing to inspect. Most tyre dealers can do this fairly quickly at relatively low cost. However, other suspension and steering problems can cause uneven front tyre wear. Worn kingpins or excessive play in swivel-ball joints will lead to prematurely scrubbed tyres.

Another important aspect of tyre care is in correct fitting. With the multiple piece wheel assembly, particular attention needs to be paid to cleanliness. The wheel itself should be smooth and rust free, while the locking ring shouldn't be bent on have sharp edges. A new rubber flap, which fits in the wheel well, should be inserted when renewing the tyre.

Dunlop also says that some operators use old tubes when renewing the tyres. This is false economy because if the tube blows it can destroy the new tyre. With smaller tubeless tyres such as those fitted to light vans it's important to renew the tubeless valve itself. They are inexpensive but thoroughly worth while.

On the larger type of tubeless truck tyre the valves are held in place by locking rings, but the rubber sealing gaskets should be changed when new tyres are specified.

With any tyre, but especially tubed tyres, foreign bodies must be excluded from the casing. They can fret against the tube, eventually causing a leak.

Again on smaller tyres, care must be exercised during fitment. Damage can be caused to the sealing if the tyre is forced onto the wheel.

Cut tyre costs

A lubricant will help during fitting to allow the tyre to slide over the rim.

Remoulds can help the operator cut his tyre costs as they

are something like half the price of an equivalent new tyre. Reputable manufacturers such as Dunlop retread their tyres by carefully selecting those carcasses which are perfect. The carcass is subjected to a number of tests before it is passed fit and it is then rebuilt to virtually new standard. In fact the price paid by retreaders for old carcasses is currently between £12 and E25 depending on condition.

Rough road

Many larger fleet operators use their own equipment to retread tyres and in fact one operator boasts that he never buys new tyres. His fleet is supplemented by about eight new vehicles per year.

When the new trucks arrive he takes all the new tyres off, with the exception of the fronts and replaces them with his own remoulds. The new tyres are then held in stock and used to replace worn front tyres on other vehicles while remoulds are made from the original fronts.

This sounds like a sort of perpetual motion, but in fact can probably work. Operators like this are all too aware of the frightening costs of tyre replacement.

• Others seem unable to grasp the facts. One particular operator in Dunlop's experience was happy to keep renewing tyres on a fleet of vehicles which were running over very rough ground with sharp flints. When it was suggested that he built a temporary road he rejected it on the ground of cost. Yet at about El 50 per tyre he could have saved the cost of the temporary road in a few weeks.

Modern tyres — even radial ply tyres — are just about at the limit of their performance. Larger sizes will heIp the situation, but it's the operator who needs to become more aware of his tyres.

After all they are the final contact with the road.

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