Mohave County miner and our mineral wealth., 1922-08-25
OVERLOAD ABOUT AS BAD AS TOO
 LITTLE OZONE

Overlooking and under-lntlatlon have an almost identical effect on pneumatic tires. The motorist who reduces his tire pressure to gain ex' travagant riding comfort or who put on too heavy load should not over- look the fact that doing these things leads to early troubles that too often are credited to some defect in the construction of the tire.
 The skilled engineer can tell at a glance when the tire finally breaks down in this way just what has caus- ed the trouble. When he opens the carcass of the tire he finds that the piles of fabric have pulled apart and knows that the tire has been run while overloaded or under-inflated. ..
 A tire is constructed with the idea tha tit is to be inflated to such an extent that it will retain its curved outline as the wheel revolves. If there is not enough air in the tire, or if it is over loaded, the part of the tire that rests on the ground will un- duly flatten out instead of remaining rounded. This flattening is called "distortion" by tire engineers.
 Asimple experiment will illustrate clearly just what takes place within the tire when it is being reflected or distorted and why too great distortion is so destructive to tire life and why such emphasis is placed upon the inn portance of keeping this distortion down to the lowest point consistent with good riding comfort. Take g book with flexible covers and make 8 mark straight across the ends of the pages at the top. The mark should be made about two-thirds of the dis tance from the binding to the other side. Bend the book sharply across the middle. You will note that as the book bends the line begins to lengthen and assume diagonal position. This means that the pages have moved, some of them a considerable distance. A tire is built up of leaves, resting one upon the other, just as the pages lie one upon the other in the experi ment just outlined. But there is this essential difference, that the pages are not fastened together and slip over each other easily when they are bent, whereas between the. plies of a tire are layers of rubber gum which bind the plies together. When the plies are bent out of position they can not slip over each other as the pages do and if the tire is not to be injured there must be no greater distortion of the plies than is afforded by the stretch in the layers of rubber. If there is too much distortion the lay CTS of rubber will be stretched too far and will gradually be torn away from the plies of fabric.
 It is pretty we'll understood that a tire as cured is approximately the shape. it is to assume when fully in- Hated. This is highly important feature of tire construction for only by curing the tire in this shape can the minimum amount of strains be limited within the tire structure it. self. .. --,, 4... .4
 When the tire is inflated and sup porting load it assumes a shape quite like the shape pictured. It will be noted that there is a decided flat tening of the true circular shape the tire originally had an da short bend- ing of the plies as shown at "E" and owing to the tire being constructed of several plies of fabric, there must be some differentiating medium to balance the difference between the movement of the inner, intermediate and other plies of fabric. Also some bonding medium to tenaciously hold the plies together enabling each to move somewhat independently of the others and still allow the complete tire section to act as unit.
 The best bonding medium for this has been found to be compound rub Der, consequently each ply of fabric is impregnated and coated with h thin layer of this highly developed sub stance. In addition to acting as a bonding medium this layer of rubber also functions as protecting coating