TYRES IN SUMMER

Ashburton Guardian, Volume 59, Issue 40, 26 November 1938, Page 9

TYRES IN SUMMER

INFLATION NOTES.

WHAT ENGINEERS SAY. In summer driving, when discomfort firom heat prompts a motorist to remember the warmth of his tyres no should remember that the advice of engineers is still only “proper inflation.”

It is a bugaboo, they say, to worry about increased pressure. Extremes of summer heat push up the pressure reading four of five pounds still well within safety limits. The slight added pi'essujre is unavoidable and it is better to put up with it than injure the tyres by “bleeding” them during use. Danger may come with letting out air in the midst of a day’s run, under the mistaken idea that atmospheric and road heat have bloated the tyres to bursting point. In reality, the greatest cause of heat is flexing in the walls of a. softened “shoe.” If some of the air is let out, increased flexing drives the temperature still higher and aids in oxidation, or “rotting,” of the rubber. Continued riding under ‘these conditions brings quicker, wear in all parts of the tyre, plus the menace of ■•blowouts, state the engineers. It is stated authoritatively that lowpressure tyres have increased the danger of under-inflation because of the higher percentage of air lost when a few pounds of pressure escapes. Heat that drives upward both tyres tern-' perature and pressure, contary to popular belief, comes from “bending, pulling, and twisting” of tyre walls and not from contact with the roadway. The danger of high heat is best offset by keeping the tyres inflated to their stated pressure, thus preventing friction within the [rubber when the car’s weight forces the tyre out of shape. Chasing of bulge around and around the tyre as the car moves over the road, though is may mean a few pounds reduction in pressure load, is held to do much greater damage by weakening the rubber. Light is an enemy of tyres and the strong sunlight of the summer months should be home in mind in this respect Engineers advise the keeping of cars out of sunlight when possible.