LARGE MILEAGE.

Auckland Star, Volume LXVIII, Issue 236, 5 October 1937, Page 18

LARGE MILEAGE.

CARING FOR TYRES.

CAREFTTL INFLATION. HEAT AND COLD EFFECTS. To natisfy modern motoristn, car tyres must provide adequate cushioning, with a minimum amount of power consumption. They must support the en-

tire load, and transmit efficiently the enfrine's power, as well as the retarding power of the brakes.

Tyres rnunt also provide amf.ie prip of the road surface, run with an appreciable decree of eilonce, and last lonjr enough to |a)ove economical. Extensive research, constant experiment and actual road teste have produced modern tyres endowed with properties which meet the demands mentioned above.

Before it can fulfil its mission satisfactorily, however, the modern tyre must be maintained at the correct intin tion recommended by its maker. Automobile tyres to-day are designed and built to do their arduous work when supported by definite air pressure, for the air carries the load.

No Guesswork Possible. The degree of pressure is not a matter of guesswork. Instruments in the tyretesting laboratory determine the pressure under which each size of tyre will •live maximum mileage under a specific load.

The tyre laboratory alpo reveals how tread wear and casing fntigue results in loss of mileage through running tvres with varying degrees of under-inflation. The following figures illustrate how under-inflation militates against long tyre life, and conveys clearly to motorists the loss of mileage and money that are inseparable from driving on underinflated tyres:— t'ndrr Inflation. Loss or Mrjeago. 1° p.c 5 p.c. 1"» p.c 2<t p.c. SN> p.c SO p.c. -•"• P-c 4O p.c. HO P.c .-.() p.c. B*i p.c ed |~,.. +•> P.C H.-. p.c. 60 p.c 7u i).c. Thus we see thnt if a motorist runs his tyres inflated to, say, 2-lllj per square inch when the air pressure should be 301b per square inch, he is deliberately sacrificing 30 per cent of the mileage built into the tyres. Only by having corect air pressure in tyres can drivers expect them to meet the demands of modern motoring.

Effect of Heat Changes. Manufacturers say that car tvres fitted in winter average 30 per cent longer weor than those fitted in the warmer months.

-This statement is based upon information resulting from study and tests of the operation of tyres on hundreds of cars, trucks and buses on all kinds of roads.

The reason for the increased mileage is obvious when some of the peculiarities of tyres are known. A tvre's greatest enemy is heat. In summer time the combination of hot weather and fast driving generates sufficient heat in a tyre to increase greatly the rate of wear.

In the autumn and winter, however rain, frost and cold definitely add to the life of tyres by keeping them cool. Also average driving speeds in winter are lower, and this contributes further to lengthening the life of tyres. The net result it* that motorists who replace tyres m the autumn and winter have the advantage of safe, anti-skid traction when driving conditions are most hazardous, and have these tyres practically as good as new for the summer months