The Waterbury Democrat., 1937-04-22
Rubber Inch Shields
 Motorist From Death
Auto Tires Contain More Engineering Than Any
 Similar Amount of Material-Tre Trends Change

vantages, easier riding and ir11- proved appearance.
 When the 17-lnch tire was intro- duced, 1t was mounted on drop center rim, development import ed from Europe, and known over there as a well base" type. AL though this rim has proved gener- ally satisfactory, some trouble has been experienced because the tube, which expands into the well or center groove. may be pinched be- tween the rim and tire bead. Rims used with 17-inch tires were from 40 to 50 per cent as wide as the tire cross section, measured from one Side-wall to the other.
 In order to give greater stability
 and to reduce the likelihood of tube pinching, the rim width has been increased on the 16-inch wheels until it is from 60 to 70 per- cent as great as the tire width.
 Perhaps you are wondering what became of the extremely low-pres- sure tire that caused so much talk a few years ago. The answer is found in the fact that the low pressure tire, using but 10 or 12 pounds of air, was somewhat ahead of its time. Steering equipment and other parts of the automobile were designed for higher pressures, and would not work satisfactorily with the huge doughnuts. It hap pens that 1t is somewhat more than an overnight job to change a chas- sis completely so as to use radically new tires, so the tire had to retire into the background and wait until the motor-car engineers were ready for it.
 It is significant that tire pres sures are dropping constantly, and are some eight pounds, on the av-a craze lower this year than last. The tendency, in the belief of J. F.. Shea, manager of the Goodrich Silvertown Stores, is constantly to- wards lower tire pressures, and eventually the levelof the doughnut tire may be reached. When that time comes, motor cars will have been engineered to a point where hard steering, creeping, Shimmying and other troubles that caused the back tracking from extreme low pressures, will not enter the pie ture.
 The introduction three or four years ago of very low pressures had parallel in the early 1920s. In 1922-23, tires inflated to pressure of 60 and 70 lbs. were used. Then came the early balloon tires, with pressures as low as 25 lbs. But cars were not ready for them, so the pressure level rose to 32-36 lbs. From there is took another unsuc- cessful jump to the 12-15 lb. level, and bounced back to the present 22-23 lb. region. But the tenden- cy is ever downward, so that you can expect true-low pressure tires within the next few years.
 The perfection of larger tires using lower pressures and running on smaller wheels with wider rims is one way engineers have contrib uted to greater efficiency of the rubber inch. But no engineer has succeeded in improving drivers along with the tires, so that blow outs and other trouble resulting from carelessness will continue to occur.
 It is the habit of Goodrich engi- neers to visit retaining plant yards, the graveyards of worn-out tires, and examine the corpses to learn what brought them there. It is a sad and dangerous story that is read in many a crumbling rubber ring. And one of the most com mon themes is improper imitation. If motor car owners would pay more attention to imitation of their tires, they would reduce appreci- ably the expense, danger and trou- ble they otherwise endure.
 MT. Shea suggests that, because underinflation is a more common evil than overinfiation, the driver makes it a habit to put about two pounds more air in each tir tehan the manufacturer recommends. when he uses the free-air hose. Thus. if your front wheels are sup posed to have 9 lbs. and the rear 28. play safe and put in 24 and 30 lbs. respectively. Remember, too, that new tires and those that have been on the spare wheel for sey- eral months will lose air more rap- idly for time than tires that have been exercised" That is one of the peculiarities of rubber. So, for the first several days, check the pressure every other day. Then check 1t two or three times a week for while, and finally every week.