Early Care of Tyres Pays
Page 53
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T" ' views of some of your readers on the subject of tyre economy, which have appeared in recent issues
of your jciumal, were very interesting. The matter
indeed merits particular consideration when vehicle operating Costs are.-so high, and I would like to give my point of view on some factors which have a bearing on
Lyre fife. • Success in regrooving tyres depends largely upon the man on the job and his ability to determine the condi tion of the casings, i.e.. whether sufficient tread be available for a good cut. Whilst I agree that certain types of tyre issued in eonnection with mileage contracts. may be designed especially to facilitate regrooving, disagree with the suggestion that other commercial
covers are unsuitable for this. I have successfully
regrooved even small-car tyres witlrout damage to the casings, and these have, later, been accepted for makers' remoulds. Recently, I have done the same thing with a' variety of covers issued to a p.s.v. operator.
The secret of success in regrooving is knowing when to approach the job. Where safety is involved, this should not be done lightly. Where I disagree with certain views expressed by other correspondent's, is in their tying up of regrooving with tyre economy. To remove material from the tread must surely reduce mileage. In my view, the time to remove a tyre from service is when the manufacturer's warning — the breaker strip or cushion rubber-appears. Any rubber removed artifically prior to this stage, is a dead loss in respect of mileage. The regrooving of .tyres is therefore a matter of road safety, not economy.
A more intelligent approach to improving Lyre mileage is to educate those responsible for the operation and maintenance of vehicles. I have often been dismayed at the lack of knowledge displayed by drivers and others responsible for lyre welfare. In fact. few drivers arc tyre conscious, whilst Many. I am afraid, regard tyres as a necessary evil. The two most prevalent causes of rapid and abnormal wear, also of carcase failure. are overloading and under-inflation.
Sometimes one hears such remarks as " there are no tyres like the first set." The truth is probably that the
vehicle itself is not so kind to the next set. There may be steering misalignment, sloppy axle assembly, maladjustment of brakes, etc. There is also what may be
termed "positional wear," caused by running a tyre too long on one wheel. Periodical tansposition and reversal of rotation can do a lot of good.
Kerbing is a "casing-killer," causing concussion fractures of the plies and abrasion of the walls, the tube may enter the cracks, causing failures, possibly long after, when kerbing has been forgotten.
I would like to see-some improvement in the direction of wheel design. Hand holes were once worthy of. the
name and one could pass a hand through to contact the inner valve. It seems that in recent designs. the brake drums are occupying more space and reducing the accessibility within the Wheels. The four-piece wheel, the continuous locking-ring gutter, bad .joints in flanges and the two-piece split flange are, to my view, anomalies which have appeared when design should have improved in the light of experience. Whatever pattern a wheel may take, however, it will still require regular attention by scaling and cleaning, followed by a coat or two of paint.
Returning to the matter of tyre economy. I would emphasize that the time to apply practical Methods of maintenance is when the tyres are new, then when the time for removal comes, a decision can be taken regarding reconditioning, whether it be by retreading or remoulding. by the makers or others. The decision is made easier when proper tyre economy has been practised throughout.
Inverness. R. M. Rowtrv.
SOME of the observations on lyre • economy and the damage done to tyres by the split rims of two-piece wheels have interested me considerably, and no doubt
many others whose tyres have been ruined by this cause. One contributor referred to the placing of a rubber pad behind the rim ends as being crude, but to me this seems no more so than the contraption which makes it necessary. To me it is strange that public criticism has not been levelled at the split rim long ago.
The ease of fitting and removing tyres with the three-piece wheel should make it the obvious choice. No sledge hammer tactics are needed, and there are no casualties in tyres, wheels, rims or men. The removal of one broken split rim under emergency conditions should convince even the most dense operator of this point. Incidentally, the discarded parts must be a familiar sight to the collectors of scrap, both here and abroad.
In fairness to these rims, however, • I would add that . we have found tyres to vary considerably in the punish' ment that they can take from the rim ends. The heavier, thick-walled types appear to be almost irnmune from the digging-in action, whilst the lighter, more flexible types soon suffer.
As an instance of the great durability of the threepiece wheel. I would mention that a set for 34 by 7 on a Leyland Cub was in excellent condition after 12 years
and 250,000 miles of running on quarry and building work. These wheels gave no trouble.
Eden thorpe, Doncaster. A. S. HARRISON.
WHAT GEAR 'FOR 'STARTING?
REPLYING to the letter by E. J. Cooke, Published in Your issue dated December 7, 1 really do not know whether to belive what he says or the letter from the public relations officer of London. transport. It is certain that at least 90 per cent, of the drivers of the RTW bus start off in second gear: This, as I stated in a previous letter, applies whether the vehicles be full or nearly empty. .
High Wycombe. • R. B DAVILS.
[1 understand that London bus drivers are instructed to use all four gears during their training period and when they pass the Ministry of Transport tests at the end of the training period. However, they are advised to use second gear when starting from rest, on level ground,• for the comfort of the passengers. Technically, f would prefer to see all four gears used every time when moving away front a point, because there is less slip in the fluid coupling, and therefore the temperature rise of the oil is not so great as when second gear is employed from stand J. Co r-rost.1