Arizona republican., 1920-08-01

tages as a cushion type tire like the Kelly caterpillar
 If the advertising of some of the tire companies who are featuring pneu- matic truck tires is examined it will be noticed that the figures which they give regarding costs, economies, etc, are based upon comparison of the performances of their tires against sol ids mot against the caterpillar.
 There are several reasons for this.
 One is that the pneumatic truck tire today is going principally on to trucks of individual owners, whose experience
 with truck tires has necessarily been
 limited. whereas a large proportion of
 caterpillars are being placed on the fleets of large truck operators, who keep accurate cost records and whose
 experience with tires has been broad
 enough to enable them to judge intel ligently as to the merits of the various
 types. The individual truck owner has jumped from solids to pneumaticS; the fleet owner has experimented with many different types and is settling on caterpillars Naturally, the manufac-
 turers of pneumatics are advertising l only the cases where their tires have 1 been brought into competition with solids.
 | Let us see just what advantages are
 claimed for the pneumatic.
 | First is it's greater traction. But the | caterpillar, on account OI US peculiar tread, has traction qualities as great as | if not greater than, any pneumatic. It | has been and is being successfully | operated without chains under all sorts of conditions-in the mushy oil fields, 1 for instance, and in the depp sand of | some of the southern states and west I ern deserts. Not only does it's system of side vents allow the caterpillar to get foothold in soft ground, but on hard highways it gives equal traction, l the side vents doing away with the so- called traction wave which is the cause | of so much lost power in the case ot
 the ordinary solid type tire, and its resiliency preventing slippage.
 | Second, resiliency. The pneumatic | is of course much more resilient than a
 solid tire, but tire carrying from 90 | to 160 lbs. of air pressure to the square inch is not exactly soft. and it is a I question whether properly inflated II pneumatic is as resilient as a cater pillar of corresponding size. The side 1 vents Of the caterpillar, which allow
 instant expansion of the rubber under
 load pressure, give it a resiliency un-
 believable to anyone who has not rid den on a caterpillar equipped truck. Third. higher speed. This brings UT
 a question which is causing a great
 deal of controversy among truck and
 tire manufacturers. A motor truck is designed to operate at a certain rate O1 SDceu, anu 0l lildl SpcCQ OC lAiIi CcaSCC by reducing the gear ration, the car rying ability of the truck is impaired If, on the other hand. the carrying abil- ity is maintained at the higher speed
 the governor must be opened and the
 ton and frequent repairs and adjust which means a great increase in vibra- ton and freqpent repairs and adjust ments
 Higher speed also calls for greater
 bralxing abilfty. Brakes designed fol
 use at lower speeds and called upor to meet the demands of fast trucking will require frequent renewals if any degree of safety is to be maintained. Another factor bearing on the higher speed argument is the matter of truck speed regulation by governmental ae- tion- The question of road mainten- ance is a serious one, and it is claimed by many competent authorities tha fast trucking does more damage t highways than heavier loads carried at slower speed Roughly speaking, ; 7-ton load carried on caterpillars at ; | reasonable rate of speed does less dam age to the road than a 312 ton loat flying along on pneumatics, and sine action toward the curtailing of trucl speeds has already been undertaken b, some states and in all Likelihood vii be in all, this is a point worth consid ering.
 | Fourth. economy. This is the strong est argument of all Tn favor of tn