CARE OF THE TYRES.

King Country Chronicle, Volume XXVI, Issue 3448, 22 November 1932, Page 3

CARE OF THE TYRES.

Every day thousands of pounds are thrown away by motorists, and a further huge sum is added to their running costs, through 'neglect of their tyres. A motor vehicle only functions in proportion to time, care, and inspection given to it, but how many motorists include tyre inspection under this heading? It is very dangerous to run an engine short of oil, but how many realise it is equally dangerous to run their tyres short of air? The tyre manufacturers make a tyre suitable for every vehicle at present being manufactured, and issue, in printed form, information showing the correct load any tyre should carry, and the right air pressure necessary to produce medium riding comfort, and minimum fatigue in steering. Beneath the rubber tread on a tyre is a carcase of cotton, built up to carry a definite load. The sidewalls of this carcase are so constructed as to flex without fracturing the cotton. The tyre pressure recommended for any vehicle is such that a motorist can take advantage of this flexing without causing damage to the tyres, but should this pressure be maintained at a higher or lower level than that recommended, the motorist lays himself open to serious trouble at a later date, the interval of time being controlled by the degree of over —or under —inflation. In an under-inflated tyre, the flexing of the sidewall sets up friction, which causes heat. Rubber is a bad conductor of heat, and cotton loses its flexing qualities with increased temperature. The result is that either the cotton cords will fracture, or the rubber will separate from the cotton, thus weakening the sidewalls of the tyre, possibly causing complete collapse at a very early stage in its life. A'n over-inflated tyre compels the tread to assume an incorrect contour, which does not allow the full tread width of the tyre to come into con-, tact with the road surface, so the tyre load is carried by only a portion of the actual tread. That portion is over-loaded and in consequence, generates excessive heat. Immediately underneath the tread is a section of what is known as “cushion”; in other words, a layer of rubber around its circumference, which is softer than the outside tread. This acts as a shock absorber, should the tyre be ever-inflated, the shock will be absorbed by a small percentage of that cushion, and the benefits which should be obtained are not only eliminated, but the shock and heat are transmitted to the carcase of the tyre, which deteriorates lyPressure, however, while a very important factor, is not everything to be considered when caring for tyres. Few motorists appear to appreciate that it is possible to wear the tread completely off any tyre in an extraordinarily low mileage should the wheels of the vehicle be running out

of alignment. You cannot see in many cases when looking at a vehicle, whether or not the wheels are running in line, and it is necessary to have them checked by your service agent should you wish to obtain from your tyres the maximum life built into them by the manufacturer. There is also a further condition which requires consideration, that is, cuts in tyres. Should a tyre receive a cut which penetrates the tread rubber, and exposes the carcase, this cut or hole forms a passage for all foreign matter, including water, into the carcase. The greatest enemy of ail is water. In running on wet roads the injury becomes filled with water, and the cotton in the carcase soaks up some of this water like blotting paper. This eventually causes the wet cotton to separate from the rubber, and soon a section of the tyre had no resistance to the internal air pressure, beyond the rubber forming the tread or sidewall. This often results in a blister, and eventually causes a burst, which ruins both tyre and tube. A little time spent on inspecting the tyres on your car will be amply repaid by the fact that it will be possible to obtain maximum “life” from them. The following are the major points, which, when checked, will go a long way toward achieving this end: — 1. Remove all tyres periodically. 2. Inspect rims, removing rust and giving a coating of stock black or similar solution. Inspect the inside of the covers for pieces of foi’eign matter or small fractures of the carcase, due to concussion bruises incurred during running. 4. Inspect the treads for small cuts, embedded flints, and the like. 5. Inspect the tubes for porosity, rust marks, damaged or leaky valves, loose particles, etc. 6. Re-fit the tyres, and inflate to correct pressure. 7. Test wheel alignment and steering connection, in order to ascertain whether any excessive play is to be traced between the steering wheel and in the movement of the wheel on the hub. Your dealer will quote you a small inclusive charge for this service, a charge which will no doubt be saved over and over again by the extra tyre mileage achieved. Finally, test your pressures once every week.