STUDY OF TYRES

Hawera Star, Volume LIII, 19 August 1933, Page 12

STUDY OF TYRES

SPEED GENERATES HEAT NITROGEN USED FOR INFLATION LESS RISK OF FIRE. The men who race cars on the speedway are always trying to devise new ways of building up speed and adding safety as a compensating factor. Each year brings its new way of helping the car to beat the clock. Experts have recently been making research studies on the heat set up in tyres travelling over the bricks of the Indianapolis speedway at the average rate of approximately 120 miles an hour, and at approximately 160 miles an hour in the straight stretches of the track.

As each car completes its 25-mile trial, two men in white overalls go out with boxed instruments to measure the heat generated on the rubber tread by the high speed run. While one applies a tube not unlike that of a stethoscope to the surface of each tyre, the other manipulates controls and watches dials from which exact temperatures are taken. What they have' been seeking is differences in the heat shown between front and rear “shoes” after the contact of rubber against bricks. The temperatures thus found are taken back into headquarters and recorded. It may take weeks or even months, to isolate the scientific facts the research men are seeking, but when found they are passed along to the production department for such practical application as may be possible. Experience of years has taught the pilots and mechanics that trouble is more likely to develop in right rear tyres than in any of the others on a racer’s wheels. The reason is that the right rear being on the outside, it is subjected to greater strains in making the turns, because the revolutions are somewhat faster than the tyres on both left wheels: The traction is more severe and the consequent wear on the tread is greater, due to weight transference caused by' centrifugal force plus driving stress. Nitrogen gas was used this year to inflate the tyres for the Indianapolis “500” race. Previously 7, both air and oxygen have been used, and fires have been known to result when blow-outs have happened at the same precise instant that there was back-fire from exhaust or cylinders. Both air and oxygen are more likely than the nitrogen to cause fire. Under these conditions and for that reason the nitrogen was used.