Tires for Commercial Vehicles.
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By Henry Sturrney.
The pneumatic tire for goods wagons and other vehicles carrying dead loads is not a practical proposition, on account of its short life, its uncertainty, and the heavy expense of renewal, but it undoubtedly possesses some advantages which the solid tire of to-day lacks. So far as my experience goes, the tire question is one of the most difficult and serious problems with which the commercial car manufacturer has to deal. The tire which we have in almost universal use today is, excepting the Matter of the quality of the mixture of which it is made, and the degree ot certainty of its attachment, but little in advance of what we had to years ago. Some tires are made up in strips, which are then forced into the grooves of the rim, the ends being united by wire. If this wire breaks, which it will do occasionally, and which it will do generally before the tire itself is worn out, it is a practical certainty that one or other of the ends will work itself out of the rim; the tire will gape, and eventually roll off ; any partially-worn tire, which has so left the rim, is virtually done with. In districts infested with tramways, the side stresses upon such tires are very great, and much inconvenience and expense is caused thereby.
Now, latterly, we have had another form of tire put before us by the tire manufacturer, and this certainly appears to present advantages over the earlier patterns. These tires are known as " banded " tires, and the makers charge a considerable amount more for them. They are formed of. a continuous body of rubber, moulded upon a steel rim, and vulcanised to it. It is manifest that, if the vulcanisation has been properly carried out, a tire such as this cannot separate from its steel support, and can be practically worn down to that support, whilst the rubber which is used in its construction, being all outside the rim, has, or should have, a greater efficiency for its weight, than is the case when half of it is buried in the groove of the rim. These steel
banded tires are forced on to the flat, steel-covered felloes of the wheel proper, and, were it assured that they would stay there, the solid-tire question might, I think, be considered fairly well settled—at least up to a certain point which I will mention later. Although the occurrence is rare, cases have been known in which the steel band, with its attached rubber, has not retained its hold upon the felloe rim upon which it has been forced by hydraulic pressure, and, of course, if one of these solid, continuous, steel-supported tires tends to creep, the felloe-band will wear, and its diameter will not hold up for the next tire.
In both the above-named cases, a further difficulty presents itself, and it is that, even supposing neither of the troubles in question occur, and the tire holds up to its work until it is really worn out, one has to ask—what happens then? The user of pneumatic tires can keep a spare cover handy, or carry it on his car, and can replace the worn tire in a few minutes: but, with the solid tire, the problem is totally different. A new strip, or " spited," tire cannot be put into the rim without special appliances, which are not to be found in all towns, and a new steel-banded tire cannot be replaced without powerful presses, which are equally unattainable locally. Hence, when a tire requires renewal, the motor is perforce out of commission for at least three days, and probably for a week, while the wheel is being sent to the tire or wheel makers for the replacement to be made, or, if, as happened in one case which came under my notice last week, the tire makers and the wheel makers have both shut their works for a week for a holiday time, the motor may be the best part of a fortnight " hung up " from this cause. To the commercial man, this means a great deal, for a deprivation of the use of his vehicle, perhaps in the busiest part of the season, even for a day, is a serious matter.
I believe there are solid tires on the market with detachable rim-flanges, and this idea seems to be a practical one, although I have had no experience with tires of this character, the two types above mentioned being practically the only ones in anything like universal use, and it would be interesting if readers of " THE COMMERCIAL MOTOR," who have had any experience of the third type, would give that experience in its columns, because, if it really does solve the tire question, the point is an important one. The chief drawback, however, so far as I can ascertain, and probably the reason that more has not been heard of this type, is the considerably-higher initial expense in so far as the rims are concerned. What is wanted in connection with solid tires to-day is, undoubtedly, some means whereby a worn or damaged tire may be replaced by the driver as readily and as quickly as a worn pneumatic cover can be changed, and, until we get this, it is quite certain we cannot 'consider the tire question finally settled. It is almost needless to add that the farther the user of the car is from the centres of manufacture, the more strongly will this point appeal to him, and, in the case of isolated users in the Colonies and such-like distant places, the matter becomes one of really serious importance.