So much has been written about puncture proof tires and spring wheels, which would make pneumatic tires no longer necessary, that everyone is inclined to be very skeptical toward any invention of this nature. The records of the United States Patent Office at Washington show about three thousand patents as evidence of the efforts of inventors along these lines. Solid rubber tires of various forms of con struction have solved the p,roblem for many strongly-built automobiles, but it is a well-established fact that the pneumatic tire or its equivalent is an absolute necessity on the ordinary form of pleasure vehicle, as it is usually operated. Perhaps the best substitute and ne-arest equivalent to a pneumatic tire is what is known as a "fill ( d tire," which consists of an ordinary pneumatic tire inflated with an elas tic. soft, spongy substance instead of air. The method of manufacture employed is to inject the filling material in a liquid state under pressure, and to thus inflate the tire to whatever degree is desired. The main difficulty has been that the user is compelled to send his wheels, tires, and inner tubes to the factory for inflation, and that after the tires were filled there was no means by which the user could increase or decrease the inflation to suit his own particular case. "Newmastic" is the only one of these tire fillers that is known to any extent. In England and France "Elastes" has been used quite exten sively, but this compound is said to be far from successful , for the reason that when first manufactured and injected into the tires, it requires two weeks in which to harden sufficiently to be I' sel. The main difficulty seems to be that the material continues to grow harder and harder as it gets older. "Newmastic." on the contrary, sets within a very few minutes after it is first put into the tires, and is ready to be used at once. Strange as it may seem, this compound appears to improve with age, remaining soft and resilient at all temperatures from 15 deg. below zero up to the burning point. In order to overcome the objection of shipping wheels from distant points to the factory, and also to enable the user to vary the degree of inflation of him tires at will, a very simple form of uni versal clincher rim has been hlvented. :????: i:t??!?? ????l:::????; :???? r:!:a ???? t ?????? ' it into two equal parts by removing about a quarter of an inch from the cen ter of the rim all the way around. The inside half is securely fastened to a plain steel band upon the felloe of the wheel. 'The outside or removable half of the rim slips over this band, and is drawn to ward the permanent half by a stiff ring which is drawn u p by ordinary bolts through the felloe o f the wheel. I n this manner the width of the clincher rim may be slightly varied, and the edges of the clincher tire may be drawn closer together than the standard clincher measurement, or may be left sl ightly farther apart. This variation in the width of the tire is so small as to cause no injury to the tire, and yet it is sufficient to take up the stretch in the casing and to afford any requir. -1 degree of inflation. This principl e of inflating a tire by drawing the casing tightly about a filled inner tube is entirely new, and applications have been made for patents in the United States and all foreign countries. Air under pressure in a tire expands and contracts according to the temperature, and an air-inflated tire is therefore subjected to a constantly varying pressure, and consequently to a constantly varying wear ; while a tire inflated wita an elastic solid material is always suJjccted to a constant pressure from withi:J., for the reason that the filler expands and contracts in substantially the same ratio as the rubber itself. A tire thus inflated is never rim cut, owing to flat running, and the automobile o wner can obtain from his tires an amount of wear which is as constant as that which he will receive from a suit of cl othes. This affords a very great saving, but the greatest advantage of all is that tires filled with the new substance are no more affected by punctures than is a p in cushion by the pins that are stuck into it ; even punctures from bolts or railway spikes will not ordinarily let the filler escape. When a really large and serious cut or break occurs in the casing, a tire bandage or gaiter will repair the damage sufficiently for the journey to be completed, and, in many cases, a tire will run hundreds of miles with such a temporary repair. Tires so inflated ride just as smoothly as tires inflated with air at the same pressure, and it is impossible even for an expert to tell from the outside of a tire whether it is inflated with this substance or with air.
This article was originally published with the title "“Newmastic”—a Reliable and Elastic Filling for Pneumatic Tires" in Scientific American 97, 19, 339-340 (November 1907)