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Page:Popular Science Monthly Volume 90.djvu/123

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Thirty cents out of every dollar spent for tires is thrown away. Why? Because automobile users do not take care of their tires

���AT the end of 1916 about three and one-half million pleasure automobiles ' were in use on the roads of the United States. During the year the owners of these vehicles spent about one hundred dollars each for tire maintenance. It follows that the stupendous sum of three hundred and fifty million dollars is an- nually spent on the tires of the pleasure cars alone. But much of it is squandered. Ignorance and carelessness are responsible for much waste. Mileage is literally built into a tire. It is the driver's task to obtain that mileage. The manufacturer has pro- vided for everything except human fallibility^ That is why thirty per cent of the money annu- ally spent on tires, in other words, about one hundred and five million dollars — money enough to interest even Rockefeller or Car- negie — is thrown away. Much of that princely sum, enough to build half a dozen

uperdreadnoughts, could be oaved by the judicious use of mere air, something that costs nothing. Under-inflation is the cause of far too much

tire trouble. Klondike gold miners, enriched overnight, have been known to light cigars with hundred dollar bills and are regarded as horrible examples

f reckless prodigality. But what shall be

aid of the sensible business man who throws


��Structure of a Tire

1. I lies uf Sea IsUnJ fabric

2. Extra coatins of finest between fabric layers

3. yi inch pure I'ara rubber cushion layer

4. 3-32 inch breaker strip of Sea Island fabric and high erade mbbcr

H inch tread, tough, resili- ent. KTipping

H inch side wall of

stroajfest rubliei

. Bead, buik

into tire for


��By Waldemar Kaemptfert

��away thirty cents out of every dollar that he spends on tires?

Air Is the Secret of a Tire's Buoyancy

It is not the rubber, not the fabric of a tire that gives it remarkable cushioning properties. It is air — just air. If you doubt this, consider the old-fashioned, iron- tired, wooden buggy-wheel on the road. What happens when it strikes a small stone in the road? It rises over the stone, you say. True. But the horse had to lift the entire load, didn't he? Whenever anything is lifted, work must be performed. Clearly, the horse was wasting power.

What happens when an air- tube strikes a small stone ? It is simply forced into the tire momentarily; the air in the tube has been com- pressed, or rather displaced at point of contact; the wheel did not have to be lifted. Do you understand now that the pneumatic tire owes its cushioning effect to air alone? Rubber is utilized simply because it is the only substance known that is elastic, air-proof and water- proof.

Measure the Load on the Tires

To save tire money you must understand that there is a very definite relation between the air-pressure within the tire and the


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