THE INDIA RUBBER WORLD 



LOCTOBEK 1, 1918. 



Specifications for Pneumatic Tires and Tubes Adopted by the 

 Motor Transport Corps. 



Till:! Pneumatic Tire Division of the War Service Com- 

 mittee of the Rubber Industry of the U. S. A. and repre- 

 sentatives of the Motor Transport Corps of the War 

 Department, held a meeting September 10 in Washington, District 

 of Columbia, the following being present: 



Tire Division — Paul W. Litchfield, chairman ; E. H. Broadwell, 



vice-chairman ; A. G. Partridge, W. O. Rutherford, J. C. Weston, 



Seneca G. Lewis, H. L. McClaren, O. R. Cook, J. S. Broughton, 



W. O'Neil, J. E. Baum, O. L. Weaver, W. W. Duncan, and 



M. L. Heminway, secretary. 



Motor Transport Corps— Major Kalb and Sergeant Wells. 



J. Newton Gunn, T. W. Thomas, G. M. Stadelman, S. P. 



Thatcher, W. E. Pfeiffer and A. R. Gormerly were also present. 



The result of tliis meeting was the adoption of the following 



specifications by the Motor Transport Corps : 



SPECIFICATIONS FOR PNEUMATIC MOTORCYCLE TIRE 

 CASINGS. SIZE 28 BY 3. 



SrEiiiuATKix X(,. 1046. 



FABRIC CONSTHUCTION. 



under a load of 325 pounds. 



1. L.ENEBAL {R) i^neui 

 accordance with this specific 

 known as 28 by 3. 



(b) The tire must give satisfactory servic 

 when inflated to 40 pounds per square inch. 



(c) Tires to be free from all defects and fully guaranteed as to mate- 

 rial and workmanship. 



(d) Tires shall be of the standard commercial non-skid design of the 

 manufacturer furnishing the same. In case of a manufacturer using more 

 than one non-skid tread design, selection of the design must be adopted at 

 the option of the Motor Transport Service. A small section of the tire 

 shall be submitted for approval before contract is let.i 



(e) The tires shall be plainly marked with manufacturer's name, serial 

 number and size of tire and marked with either tag or label in colors of 

 red, white or blue which will denote as follows: red, first four months of 

 calendar year; white, second four months of calendar year; blue, last four 

 months of calendar year. Years to be designated by square, triangle and 

 round labels or tags — tags or labels to be approximately two inches in 

 diameter. 



(f) As soon as possible it is desired that all tires be marked with the 

 equivalent millimeter sizes as recommended by the Society of Automotive 



2. Type. All tires manufactured in accordance with this specification 

 shall be of the clincher type, designed for the standard S. A. E. clincher 

 motorcycle C. C. ritn of the size 28 by 3. 



3. Construction, (a) Splices on first ply of fabric shall be gum 



(b) Carcass of tire shall consist of at least four separate plies of tire 

 duck with friction coat on two sides and skim coat on one side applied 

 a 45-degree bias. The gage of one ply fric ' 



vc spli 

 curafer 



Each ply shall have not more 

 even inches apart measured on 

 s in the tire shall be at least 

 mference of the tire. 

 ;23 by 23) from the long-staple 

 yard with an allowable variance 



shall be at least .043-inch, 



lich must be at least 



Df the tire. The spli 



3 inches apart when measured on the cir 



(c) All fabrics must be square wover 

 cotton weighing 17!4 ounces to the squar 

 of olus or minus 3 per cent. 



(d) All fabric must be thoroughly dried according to standard manu- 

 facturing practice, before it is started through the operations of rubber- 



(e) The usual methods of inspection used by tire companies in com- 

 mercial practice to discover defects in each roll of fabric shall be employed. 

 The following tests shall be used to determine the strength of the fabric. 

 All fabric shall be tested in a standard testing machine to determine the 

 tensile strength. The distance between the grips on the machine shall be 

 approximately 3 inches and the separation of the jaws shall be at the rate 

 of 20 inches per minute. Six samples shall be cut from each roll in such 

 a manner as to eliminate any unnecessary waste of material. Three sam- 

 ples shall be cut longitudinally to determine the warp strength and three 

 samples shall be cut transversely to determine the filler strength. The 

 samples shall be prepared in the following manner: unravel to 23 yarns 

 (1-inch width), heat until sample is "bone dry", and immediately test it m 

 machine. The results must show a tensile strength of not less than 165 

 pounds per inch for either warp or filler 



Beads shall be 

 immercial practice, 

 (g) One chafing strip of squart 

 per square yard shall be 



ucted with a rubber core filler as in standard 



fabric weighing not less than 



" " ig St ■ 

 5^-inch from 



upward on each side of the tii 

 the bead. 



(h) There shall be a cushion of rubber compound applied over the 

 fabric which shall be wider than the bleaker. The minimum gage of this 

 cushion shall be .0325-inch. 



i) Over the cushion there shall be a single breaker strip of open- 

 weave fabric such as is used in standard commercial practice, coated on 

 both sides with a rubber compound having the physical and chemical prop- 

 erties of a nature to form ^ perfect union between the cushion and tread 

 when the cure is effected. This breaker strip shall have a minimum width 



17^ inches. 



lAll sections for approval 

 ngincering Division, Motor 

 n. District of Columbia. 

 -As done in tread test. 



(k) 



akcr shall be ma<lc from lo-ig staple cotton and shall weigh not less 

 eight ounces per square yard. 



The tread of the tire shall not be less than "4 -inch thick in center, 

 h of which shall be the minimum thickness for the part of the tread 

 the middle of the non-skid portion. 



sidcwall of the tire shall have the 



thickness of 



4. PiivsiCAi. Measurements and Tests. Ca) Cross sectional diameter 

 of each tire inflated according to the recommended weight and load sched- 

 ule of the S. A. E. shall not be less than 2-15/16 nor more than 3.3 inches. 



(b) Tire shall be capable of withstanding water pressure of 250 pounds 

 per square inch without apparent injury. This test to be made at the dis- 

 cretion of the inspector. 



(c) The strength of the union between the plies of fabric shall average 

 18 pounds or more per inch, using the standard friction test. 



(d) The strength of the union between the breaker and tread and be- 

 tween the breaker and cushion shall average 28 pounds or more per inch, 

 using the standard friction test. 



(e) The strength of the union between the cushion and plies shall aver- 

 age 16 pounds or more per inch, using the standard friction test. 



(f) The strength of the union between the sidcwall and plies shall aver- 

 age 12 pounds or more per inch, using the standard friction test. 



5. Road Test, (a) Any manufacturer, bidding on orders for govern- 

 ment business, must be prepared to meet the following testing conditions; 



(1) No tires are to be given consideration by the Government unless 

 the company submitting the bid tenders an affidavit stating that they main- 

 tain and properly check up tests on cars to properly test their pneumatic 

 tire products and that these cars deliver an average of 2,000 tire miles 



(2) The cars, speeds, loads and road conditions must be such that the 

 tires are properly tested and the Government may appoint an inspector to 

 see that the above conditions are complied with. 



(3) A successful bidder must supply an affidavit before delivering any 

 tires to the Government stating that the tires to be delivered are practically 

 duplicates in construction and material of tires which he has previously 

 tested and a sufficient number of tires satisfactory to the Motor Transport 

 Service, at least six tires, have averaged on the rear wheels at least 4.000 



6. Lining. The inside of each tire shall be properly lined in accord- 

 ance with the standard practice of tire manufacturers. 



7. Flaps. Each tire casing shall have a flap cemented into the inside of 

 the casing in accordance with the standard commercial practice. 



8. Compounds, (a) Tread— The tread shall be made from and have 

 the characteristics of a compound containing at least 65 per cent by vol- 

 ume of the best quality new wild or plantation rubber. Content of sulphur 

 shall not exceed 8 per cent by weight of new rubber used. Compound 

 shall be free from ingredients known to the rubber trade as "oil substi- 

 tutes." The minimum tensile strength of the tread rubber shall be 2,600 

 pounds per square inch and shall have an elongation of not less than 450 

 per cent (2 inches to 11 inches). The set shall have a maximum of 25 

 (400 per cent or 2 inches to 10 inches when elongated for 10 minutes, 

 using 2-inch sample with 10 minutes' rest before measuring). 



(b) Friction and Cushion — These shall be made from and have the 

 characteristics of a compound containing at least 75 per cent by volume 

 of the best quality new wild or plantation rubber. Sulphur content shall 

 not contain more than 8 per cent by weight of new rubber used. 



(c) Sidewalls — The sidewalls shall be made from and have the charac- 

 teristics of a compound containing a minimum of 65 per cent by volume 

 of the best quality new wild or plantation rubber. Sulphur content shall 

 not be more than 8 per cent by weight of new rubber used. Reclaimed 

 rubber to the extent of 15 per cent of the total compound is allowable, but 

 the amount and kind must be declared by the manufacturer. The minimum 

 tensile strength of the sidewall rubber shall be 1,500 pounds per square 

 inch with a minimum elongation of 450 per cent (2 inches to 11 inches) 

 and a maximum set of 25 per cent.- The compound shall be free of ingre- 

 dients known to the trade as "oil substitutes." 



(d) The total sulphur in any of the above compounds shall not exceed 

 8 per cent of the weight of new rubber used except as follows: If the 

 manufacturer desires to use sulphur-bearing mineral fillers, thereby causing 

 the total sulphur to be over 8 per cent of the weight of new rubber, he 

 may do so, but shall submit for analysis a sample of the fini'shed unvulcan- 

 ized stock. Such stock shall not show a sulphur content in the acetone 

 extract of over 8 per cent of the weight of new rubber used. 



9 Inspection. The Motor Transport Service reserves the right to make 

 any inspection, test or analysis necessary to insure the product meeting all 

 requirements of this specification. 



10. Packing. All tites shall be spirally wrapped according to standard 

 practice and properly labeled on the outside showing size, type and name 

 of manufacturer, and marked with either tag or label in colors of red, white 

 or blue which will denote as follows: red. first four months of calendar 

 year; white, second four montlis of calendar year: blue, last four months 

 of calendar year; years to be designated by square, triangle and round 

 labels or tags, tags or labels to be approximately two inches in diameter. 

 Tires shipped ior original equipment of cars shall be packed as specified by 

 customer. In the case of oversea shipments, the specifications covering this 

 shall be applied. 



Specification No. 1065, 



FABRIC CONSTRUCTION. 



ccordance with this specification shall be of fabric construction of the size 

 :nown to the trade as 29 by 3i/. 



(b) The tire must give satisfactory service under a load of 400 pounds, 

 vhen inflated to 45 pounds per square inch. 



(c) Tires to be free from all defects and fully guaranteed as to mate- 

 ial and workmanship. 



(d) Tires shall be of the standard commercial non-skid design of the 

 nanufacturer furnishing the same. In the case of a manufacturer using 

 nore than one non-skid tread design, selection of the design to be adopted 

 s at the option of the Motor Transport Service. A small section of tbc 

 ire shall be submitted for approval before contract i5 let.i 



