Mohave County miner and our mineral wealth., 1920-06-12
Solids or Pneumatics---W Which?
By s. V. NORTON.

the Truck and Tractor of the Society of Automotlve Engineers held in Chicago a paper en- titled Relation of Solid and Pneu- matic Tires to Motor Truck Efficien- cy" was read by s. V. Norton, of the B. F. Goodrich Rubber Co.
 The following is the first install ment of an abstract from his paper which has been pronounced by experts as the most authoritative treatment of the subject ever made. MT. Norton is widely known as transportation en- gineer, tire expert and as the author of 'Motor Trucks of America" and ''The Motor Truck as Aidto Busi- ness Profits. The Subject will be covered in three instauments. The second will appear in this section next week.
 The question of whether heavy motor trucks should be equipped with solid or pneumatic tires is one of the most important problems confronting the motor world today.
 Needless to say, each type has its advantages and limitations. If that were not true one type would be used exclusively and the other would be discarded. It is apparent, therefore, that careful study of all factors in volved should be made before deciding which tire to use. For the purpose of this discussion the factors to be considered may be divided into three groups, as follows: 1st the engineer ing features; End, the practical oper- ating features; and 3rd, the features of tire service in the field.
 The information I shall give you is not thereotical, nor based on the experiences of selected operators whose delivery problems would invar- iably point to the same conclusion, but rather a composite on the opinions of hundreds of truck operators and their mechanics engaged in handling all kinds of merchandise.
 In the first place, it should be con- idered that conclusions which appear sound today may have to be modified in them by changes that are gradually but constantly taking place. For in stance, truck design is being altered and improved; tires are being built better and stronger; roads are being improved, and experience is pointing the way to the more intelligent use of motor trucks through systems and de- vices heretofore unknown. Another point to be considered is that trucks are used to move freight under wide ly differing complex circumstances. Conclusions based from experiences in one case might not be borne out in oth- CT cases. Viewing the problem from this angle, have sought information not only from truck manufacturers and their engineers, but from truck salesmen and operators in all parts of the country las we'll as from tire dealers and those upon whose loca service successful truck operation de, pends.
 The functions of tire equipment are Ito secure traction; 2-to cushion the mechanism and the load; 3-tt protect the road. To perform these functions, three types of tires ar' available: solid, cushion, and pneu matic. Since there are relatively few cushion tires in service at present w. can confine our discussion to the solit and pneumatic types.
 It is safe to say that at present thu accepted field for each type is as fol lows: pneumatics on trucks up to l + tons capacity and solids on trucks O 312 tons or over. Between these tw, capacities the field is debatable, am the choice cannot be made intelligent ly without careful analysis of tn important factors involved. In talk ing up the engineering aspects shal deal briefly and frankly as a laymel and not as truck engineer.
 The first point to be considered il this respect is the difficulty encount cred inusing type of tire on trucl different from that for which it wa intended. To place pneumatic tire on truck equipped for solids requir es, in the first place, that the wheel of the vehicle be cut down. More over, proper allowance must be pro vided for both body and fender clear ance as the larger sectional diamete of the pneumatic tires will effect tn steering clearance and the truck vii be unable to turn in so short a radiu as it did on the solids. This is es pecially important in negotiating turns in narrow streets and alleys a we'll as in garages with limited floo space.
 As the larger diameter of pneumati tires will effect the gear reduction l substituted for solids the mechanics