Your Tyre Questions Answered
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A Selected 'Nurnber of Questions and Answers Relating to the Well-being of Covers and Tubes
IN connection with the many Tyre Economy Exhibitions which are being held throughout the country, a particularly useful feature is that concerned with the answers, given by experts, to questions put by operators end drivers.
We give below a selection of those compiled following one of the exhibitions recently held in London: Q.—Is there anj means by which a driver can know that an inner rear tyre is losing air?
A —No. A driver, especially on a long run, should stop every 50 miles or so and examine all his tyres.
Q.—Is it permissible to run Trak Grip tyres the wrong way round?
A.—No. They should be run in accordance with the instructions given on the side-walls.
Q.—Should tyre pressure be reduced when a vehicle is being stored?
A.—No. Keep up the normal pressures. cover the tyres, and jack up the vehicle.
Q.—Are all makes of tyre, of the same size, designed ,to be run at the same pressure?
Q.—Is there any value in scrap tyres?
A.—Tyres unfit for retreading are treated, and the rubber is • reclaimed for " mixture " in manufacture.
Q.—Is it permissible to fit 32 by 6-in. tyres on 7-in. rims?
A.—No, except in an emergency. Q.—Is it bad for the tyres to leave a loaded vehicle standing over night?
A.—No, provided the tyres be correctly . inflated.
Q.—Can nothing be done to. prevent the scattering of coarse, sharp grit on the roads? • A.—Preventive action can be taken, and has been taken, in areas where the use of this grit is excessive. Report ,such an area to your A.T.D. or to the Directorate of Tyres.
Q.—What degree of over-inflation is permissible in view of the heat that may be generated in a running tyre?
A.—None. A tyre should not be inflated above the pressure scheduled for its size and type. Any increase in pressure created while the tyre is running is allowed for by the manufacturer in the production of the tyre.
Q.—It it advisable to increase tyre pressure if the vehicle be overloaded?
A,—No. The vehicle should not be _overloaded. If it be necessary to carry overloads, the vehicle should be fitted with oversize tyres. Your A.T.D. will advise you as to the correct sizes.
Q.—What is the average Mileage of retreaded tyres?
A.—On the average between 661 and
,• per cent, of the original
mileage. In some cases the original mileage has been exceeded; after retreading
Q.—Why is the correct pressure not marked on the side wall of a
tyre?, , • A.—Because the load of the vehicle varies from time to time, and therefore the correct pressure varies. Your A.T.D. will always give you the correct pressure for the load to be carried.
Q.—Who determines the size and type of tyre for a given vehicle? A.—The vehicle and . tyre makers,.
Q.—Why cannot the valve on the inner of twin tyres be made more accessible?
A.—The alleged inaccessibility is often due to the presence of a wrong type of valve, end sometimes to too low a pressure that causes the valve to be pulled out of position. If you have a wheel with an extra wide offset, you may obtain a valve extension which will help you in inflating and in checking pressures; but be sure that your valve is Of the correct type.
Q.-1s the correct pressure the same for each of twin tyres?
A.—Generally it. is, because on modern roads the twins share the load • equally. Sometimes (as, for instance, when the vehicle is run in a region where the roads are steeply cambered) the inner tyre may be slightly less inflated than the other.
Q.—Does a weak spring cause excessive tyre wear?
A.—It may. by causing the load to fall over to one side and thus creating an overload there. A weak spring may cause excessive tyre wear also by disturbing front-wheel alignment.
Q.—What should I do if I have a tyre failure on the road and have no spare?
A.—Contact the nearest A.T.D. and make use of the breakdown service incorporated in the tyre rationing scheme. Do not run with a deflated tyre, even with • twin, or damage will ensue, not only to the deflated tyre, but to the• good one which will be asked to carry twice its proper load.
Q.—What is the best way of removing tyres from rusty rims?
A.—It is best to avoid this difficulty entirely by cleansing the rim of rust and applying One of the preparations or dressings, sold for this purpose, before fitting the tyre. Moreover, tyres should be examined periodically and changed from wheel to wheel; in this way no tyre will be allowed to adhere to a rusty rim. Where, however, a tyre has become rusted on to a rim, a small quantity of het water • poured over the bead and the rim will be found efficacious Q.—Which is worse for tyre wear—a long journey with speeding or a short journey with many stops?
A.—As heat is the greatest enemy of rubber, and as speeding generates heat, the first of the two hypotheses is the worse for tyre wear.
Q.----How can one even the load on a back axle fitted with twin wheels and tyres?
A.—It is best to. mate .tyres of the same overall diameter and inflate 'both to the recommended pressure. Where the inner tyres show uneven wear, a tyre of slightly less overall diameter (about I in, less) may be fitted, but the same pressure should generally be maintained in inner an& outer tyres.
Q.—Is water detrimental to tyres?
A.—No, but it may make them more susceptible to cuts. Rubber that is to be cut with a knife is often dipped in water to facilitate
the process. [Water. -is not detrimental to rubber, but should be prevented from getting on to the canvas or cord foundation. —Eo.1
Q.—How can one recognize a synthetic tyre?
A.—It carries a red medallion on the side. • A tube made with " syn thetic " carries a red strip.
Q.—Why is it not possible to make a tyre wholly of synthetic rubber?
A.—It is possible in the case of tyres for cars and of the ,smaller size giant tyres. With the larger sizes, tyres made wholly of " synthetic " become far too hot in running. At present, the only method of countering thie tendency is to mix a proportion of natural rubber with the synthetic.
Q.—Do synthetic-rubber tyres operate at the Same pressure as natural rubber tyres, size for size?
Q.—Is it true that tubes made with synthetic rubber cannot be repaired in the ordinary way?
A..—It is incorrect, but greater car is necessary in effecting the repairs, and it is better to allow a qualified repairer or an A.T.D. to do them. If you attempt to patch _ a " synthetic ' tube yourself, apply several .coats of solution (allowing each to dry off before applying the next) before you put on the patch.