August i, 1903.] 



THE INDIA RUBBER WORLD 



377 



THE MERIT OF HEAVY AUTOMOBILE TIRES. 



IN a recent French work on " The Science of Automobile 

 Touring" the author, M. Leon Auscher, devotes a chap- 

 ter to the subject of tires, in which appear some sugges- 

 tions of interest and practical value. The author endorses 

 the declaration of Baudry de Saunier, that without the pneu- 

 matic tire, however great the mechanical improvements whi( li 

 have been evolved, we should never have had automobilism as 

 we now know it. lie gives credit to Dunlop for the birth of 

 modern cycling, and to the Michelins— the French tire manu- 

 facturers — for making the automobile possible. 



The first automobile with pneumatic tires made its appear- 

 ance on the Paris-Bordeaux route in 1895. The tires punctured 

 frequently, but Michel in had demonstrated the possibility of 

 traveling with carriages of this sort, and it only remained to 

 perfect the invention. Two years later a steam carriage built 

 in Dion was rolling at the rate of 60 kilometers [ = 37^ miles] 

 an hour upon the Marseilles-Nice route. "The automobile 

 rail had been discovered." The perfecting of the tire, how- 

 ever, was a longer process than the invention. Among the 

 difficulties to be overcome, the greatest was in increasing the 

 powers of resistance of the tire. The size progressed from 65 

 millimeters [ = 2.60 inches], to 90 mm. [ = 3.53 in.], and to 120 

 mm. [ = 472 in.] in diameter. At every stage it was believed 

 that the sufficient limit had been reached. But at every stage 

 experience proved the necessity for making the tire stronger, 

 and that a tire could not have too great powers of resistance. 

 Hence tires have been produced up to 150 mm. [^5.90 in.] in 

 diameter — which figure now holds the record. 



Each of these improvements further enabled manufacturers 

 of automobiles to improve their carriages from the double 

 point of view of the reduction of horse power and the general 

 betterment of the mechanism. Thus our motors can confront 

 the better type of roads with the maximum of speed, without 

 making allowance, so to speak, for the resistance of the ground , 

 All of which goes to prove that if the pneumatic tire is not yet 

 perfect, it already realizes many of the desiderata, and no 

 longer constitues a permanent discomfort in the life of the 

 chauffeur . 



Our author favors the use of wheels of uniform size on motor 

 cars, furnished with uniform tires. One advantage is that the 

 number of reserve tires to be carried on a journey is thus re- 

 duced to a minimum. The rear wheels always support a much 

 greater weight than the front wheels— usually three fifths on 

 the rear axle aud two fifths on the front. Hence the hinder 

 tires work under a greater strain ; furthermore, they are on the 

 motive wheels, which tends to their wearing out much sooner. 

 With four uniform wheels, it is possible to exchange to the 

 front wheels the back tires when they have become worn to the 

 point of being dangerous in the rear, but are still fit for service 

 in the front 



Upon ten carriages, it will be found that nine have tires that 

 are too weak. Manufacturers are apt to overlook the fact that 

 their frame work may carry considerable carriage loads, and 

 thus fail to specify tires of proper strength. Then inexperienced 

 patrons, as a rule, demand too light a weight of frame and ac- 

 cessories. It would be to the interest of tourists to provide 

 themselves with tires stronger than may seem absolutely neces- 

 sary, especially as carriages almost universally become bur- 

 dened with unforeseen accessories. What is lost in speed by 

 the use of heavy tires will be regained by avoiding accidents. 



The tire of 90 millimeters is capable of supporting a maxi- 

 mum weight of 450 kilograms [=992 pounds] per wheel, or 

 900 per axle. Now in a carriage weighing 1500 kilos [ = 3307 

 pounds], the rear axle carries normally 900 kilos and the front 

 600. The 90 mm. tire will therefore be inadequate, for it 

 travels continually at its limit of resistance. The wearing out 

 will consequently be rapid, and frequent breaks will occur, 

 while any overload— always possible — will still more endanger 

 the endurance of the tire. 



The 1 20 mm. tire, however, supports 600 kilos [=1323 pounds] 

 per wheel, or 1200 kilos per axle, which affords an excellent 

 margin for protection against accidents. Objections have been 

 urged against tires of such size, because fi) of the additional 

 difficulty, at first, in driving the motor ; (2) an additional heav- 

 iness of appearance to the eye ; and (3) in higher price. But 

 our author has found no difficulty in the management of a 

 motor carrying 120 mm. tires on the front wheels, while as for 

 appearance, he asserts that the eye accustoms itself readily to 

 appreciate a construction the utility of which the brain under- 

 stands. As for the greater first cost of the larger tires, this is 

 soon offset by the lessened necessity for repairs and replace- 

 ments. An intermediate tourists' tire is now produced, of 105 

 mm. [=4.14 inch] diameter, which is capable of sustaining a 

 weight of 1 50 kilos in excess of the normal strain upon the rear 

 axle of a carriage weighing 1 500 kilos. 



But it is not enough to secure suitable tires. They require 

 perfect care. Two chauffeurs, placed in exactly identical con- 

 ditions, making use of the same character of tires, will find 

 widely different results in their wear and tear — one outfit of 

 tires averaging two or there times as long as the other. There 

 are three things which a careful driver should avoid — the un- 

 necessary use of brakes, a too great frequency in turning (and 

 particularly in making short turns), and too brisk starts. Not 

 only the tires, but the delicate mechanism of the motor itself, 

 may be injured by brusque, short, turns. And tires must be 

 placed on the wheels with care, and not used without being in- 

 flated to the proper degree. 



DETACHABLE VS. SINGLE TUBE MOTOR TIRES. 

 BY AN AKRON CORRESPONDENT. 



A point in tire manufacturing on which manufacturers — 

 Akron manufacturers at least — have come unanimously to 

 agree is that the single tube tire is to be almost wholly sup- 

 planted by the clincher or detachable. The main reason for 

 this lies in what is asserted to be a fact, that the detachable 

 tire does all that the single tube can do on any vehicle and a 

 great deal more; that it is excelled in no point or manner by 

 the single tube tire; and in addition has extraordinary advan- 

 tages which the latter does not possess. Chief of these is the 

 " endless chain of economy." 



The claim is made, for instance, that with this tire the outer 

 case may be cut and punctured in a score of places, but as long 

 as the inner tube, the air cushion, is not injured, the tire is prac- 

 tically unharmed. And if the inner tube be punctured, it is a 

 simple matter to unfasten the outer case as much as needs be, 

 pull the tube out, patch it, and soon restore everything to work- 

 ing condition. Moreover, if the inner tube be so damaged that 

 it cannot be instantly repaired, a new tube is readily obtainable 

 — the auto tourist carrying two or three with him, no doubt. 

 A new tube can be quickly put in place and there is no expense 

 save for that ; the casing remains as before. The injured tube 



