October i, 1906.] 



THE INDIA RUBBER WORLD 



11 



A STUDY OF FLAT TREAD PNEUMATIC TIRES. 



TIIIC Hat trcMcl IxKiiii, wliicli is now on in full force, has 

 led many to look into the arguments for and 

 against this tj'pe, even when they did not intend 

 making a change. (Ithers are interested, without 

 having the time to investigate the matter thoroughlw and 

 have expressed a wish to have the question threshed out. 

 .After all, it is not a matter of any great importance; but 

 wlien one considers the popularity of this type, in the face 

 of the recent demand for round tires, it must have a hrnicr 

 hasis than a passing whim. The round tyjie is, of course, 

 the oldest ; and though tires were later made in squares and 

 horseshoe shapes, the tendencj' for several years has been 

 toward a round section, which shape liest distributes the 

 strain. 



I,et it be got clearly in mind at the beginning, that practi- 

 cally all the flat treads now made, whether Palmer, Gaulois, 

 Imperial, Michelin, Continental, Harburg, Pennsylvania, 

 O & J, or Diamond, are made in a round section, .so far as 

 the canvas and strains are concerned. The names just given 

 do not complete the list, either, because every well estab- 

 lished tire house is now making flat treads, regularly or for 

 special orders. 



It is not known just when the flat tread was first made. 

 Like almost every other commodity, the idea was probably 

 advanced long before it came into real use. The Continental 

 Caoutchouc Co. seem to have first brought the flats promi- 

 nently forward, the Michelins following closely. They 

 have now been in use for nearU' tw-o years in Kurope, though 

 the G & J and the Diamond people, who were the first 

 Americans to take them up, have onlj' been making them 

 during the past season. They are still far more popular in 

 Europe than here, though they are coming rapidly into 

 favor with Americans. The presumption has really been 

 against them, and they have not been well advertised in the 

 I'nited States; and their rapidly growing jiopularity is 

 based upon the recommendations of those who have actually 

 used them. Everybody who has ever used fiat treads has a 

 good story to tell of their steadiness, their lasting qualities, 

 and their behavior on skiddy roads. 



The disfavor in which flat treads were first held grew out 

 of an apparent weakness, which has no doubt thrust itself 

 upon everybody who looked at them for the first time. This 

 is that a flat tread, built upon a round tire, will necessarily 

 leave thick corners on each side. At first sight, it woidd 

 seem that the weight of the car, running upon these corners, 

 would make the tire bend or crimp sharply in the center of 



the tread, thus destroy- 

 ing the canvas, sooner 

 or later, along that 

 line. 



The more a man 

 knows about tires, the 

 more does this criticism 

 appeal to him, and the 

 makers admit that such 

 crimping is a po.ssibil- 

 ity, if the tires are run 

 FLAT TREAD PNEUMATIC. 1°° soft ; but having 



,,,j(pp«.„.,jaaie.,. ,- .Wfea 



the canvas built in round section largely removes this slight 

 tendency. 



Another objection sometimes brought against flat treads 

 is that they must be molded. Though rarely .seen now, it 

 was fi)riuerly common for the canvas to be wrinkled or 

 crimped in the mold, thus bringing it very close to the sur- 

 face in spots, where it ,soon wore through and burst. Some 

 tire nundirs claim to have found such flaws in some of the 



Ivuropean flats; but 

 such instances are rare, 

 and are hardly known 

 among American flat 

 treads. 



Other criticisms, 

 purely theoretical, are 

 that flat treads are 

 more likely to catch on 

 sharp stones, thus hav- 

 ing their edges gouged 

 off very .soon, while 

 K-''T Tn M> . : i I Touud tifcs would 



glance ofi'or kick the rocks out to one side. Others think 

 that a heavy side strain, catching upon the tread edge, 

 would have a better chance to tear the rubber loose from the 

 canvas. Some have also advanced the objection that every 

 increase in the thickness of the tread must necessarily take 

 away from the speed and bouncinessof the tire, making it ride 

 harder and require more power. .Another theoretical criticism 

 is, that the wider the tread and the more the road contact, the 

 more road friction there will be. meaning less speed and re- 

 siliency. They feel that when running in mud and on wet 

 asphalt, flat treads would necessarily create more suction. 

 The Collier Tyre Co., who have made a study of this very 

 point, and who, in con.sequence, have made their tires with 

 narrow, pointed trea<ls, jjrint testimonials reading like this : 

 " My car, owing to your narrow tread tires, raises verj' lit- 

 tle dust, at a time when I have met cars with flat treads 

 raising clouds. " 



.All these criticisms, as we said, are purely theoretical ; 

 but they are such that they readily occur to the tire expert, 

 have considerable weight, and have undoubtedly checked 

 the spread of flat treads. As such they must be fairly 

 stated, and balanced against the corresponding advantages. 



Those who 

 have actually 

 used flat treads 

 claim for them 

 several dis- 

 tinct advant- 

 ages; but to F AT TIrAL. T.V1N SOLID TIRE. 



rightly understand some of these, we must bear in mind the 

 importance of speed as a factor in our reasoning. Thus, 

 where the ordinary horse drawn vehicle wants as little road 

 contact as possible, because the only duty of the wheels is 

 to hold up the vehicle, the tendency is toward narrow tires ; 

 but in the case of a motor car, the drive wheels, besides 

 holding up the load, must also push the car, which means 

 that they must have a good grip upon the road. The 



