800 



THE INDIA RUBBER WORLD 



[Seitember 1, 1920. 



S. A. E. Standards Report of the Tire and Rim Division. 



THE FOLLOWING REPORT of the Tire and Rim Division of the 

 Society of Automotive Engineers, as amended and accepted 

 by the Standards Committee, was approved by the Council 

 at the general meeting of the Society, held at Ottawa Beach, 

 Michigan, June 21. These new standards require only the ap- 

 proval of the members of the Society to be obtained by letter 

 ballot. 



AUTOMOBILE RIM VALVE HOLES. 

 The Tire and Rim Division recommends that the present S. 

 A. E. standard for automobile rim valve holes be extended to in- 

 clude the dimensions for the 5, 8 and 10-inch tire rims and that 

 certain lengths in the present standard be increased. The present 

 S. A. E. standard revised and extended as recommended by the 

 Division is given in the accompanying table; 



?''" ?•« inches 3^5 A 4'A S 6 7 8 10 



^ (™"> ^ H H Hi 2A 2H 3'A 4'A 



FELLOE-BAND TOLERANCES. 



Owing to variations in the thickness of commercial tapes, with 

 the resulting inaccuracy of wheel measurements, it is recom- 

 mended that approved standard tapes be used for measuring 

 felloe-band circumferences, of which one set is intended for truck 

 and one for passenger-car wheels. 



The Division therefore recommends that the present S. A. E. 

 standard for allowable tolerances in felloe-bands be extended to 

 include the following note : 



It is recommended that all measurements of truck and 

 passenger-car wheel circumferences be made with approved 

 standard wheel tapes furnished by the Tire and Rim As- 

 sociation. 



DEFLECTION AND SET TEST OF AUTOMOBILE PNEUMATIC 

 TIRE RIMS. 



The present S. A. E. standard for deflection and set test of 

 automobile pneumatic tire rims specified the pressure deflection 

 and permanent set for 3^, 4, 4y,. 6 and 7-inch rims 'only. The 

 Tire and Rim Division now recommends the pressure, deflection 

 and permanent set for the S, 8 and 10-inch rims. The present 

 S. A. E. standard extended to include the Division's recommen- 

 dation follows : 



PNEUMATIC TIRE RIM TESTS. 

 „. ^. Maximum 



5"" ?'^= Pressure, Maximum Total 



Nommal, Pounds Deflection. Permanent 



Inches. Per Square Inch. Inches. Set. Inch«. 



y' jO 0.06 0,02 



tu ]t^ 0.07 0.03 



c^ ll" n.io 0.06 



5 190 0.12 0.06 



I 200 0,5 0.06 



i 225 0.15 0.06 



,1 250 0.15 0.06 



^^ 250 15 0.06 



The deflection should be measured from a fixed inflation load 

 of 25 pounds per square inch for 3^, 4 and 4^-inch sections, 

 and SO pounds per square inch for S-inch and larger sections 

 up to the maximum pressures given. 



MOTORCYCLE RIM SECTIONS. 



Circularization of the motorcycle industry last year indicated 

 that standard current practice includes only tire sizes which are 



mounted on the CC rim. These tire sizes were adopted by the 

 Society last winter and in order that the rim specification shall be 

 in conformity with this list of tire sizes the Tire and Rim Divi- 

 sion recommends that the BB rim section be withdrawn from 

 the present S. A. E. recommended practice for motorcycle rim 

 sections. It is the opinion of both the Motorcycle and Tire and 

 Rim Divisions that the BB rim section can be reestablished as a 

 standard should the use in the future of light weight motorcycles 

 carrying the BB rim become general enough to warrant its in- 

 clusion in the standard. 



CARRYING CAPACITY OF SOLID TIRES. 



Solid Tire Width, 36-Inch 4n.Tnrh 



3,000 

 4,000 

 5,000 

 6,000 

 8.00O 

 10,000 

 12.000 



The present S. A. E. standard for carrying capacity of solid 

 tires has been criticized to the effect that at rated truck capacity 

 an increase in the tire carrying capacities would be justified in 

 practically all sizes and would conform to general practice. 



The Division therefore recommends that the carrying capacities 

 specified in the present S. A. E. standard for carrying capacities of 

 solid tires be revised to conform to capacities given in the above 

 table. 



PNEUMATIC TIRES FOR PASSENGER CARS AND COMMERCIAL 

 VEHICLES. 



The Division recommends that the present S. A. E. standard 

 for pneumatic tires and rims for passenger cars and commercial 

 vehicles be revised so as to eliminate the 42 by 9-inch tire and 

 rim as regular equipment. This size tire is considered a special 

 application as the oversize for the 40 by 8-inch on pneumatic- 

 tired trucks and not as a regular size. It is also felt by the Divi- 

 sion that the 44 by 10-inch is now well enough established to be 

 included in the standard as regular equipment. 



The S. A. E. standard revised as proposed is as follows : 



RIM SECTIONS AND CONTOURS FOR PNEUMATIC TIRES. 



The Tire and Rim Division recommends that the present S. A. 

 E. standard for rim sections and contours for pneumatic tires 

 for passenger cars and commercial vehicles be revised in accord- 

 ance with the dimensions submitted in the following table. This 

 table has been extended to include the dimensions for the S-inch 

 rim- recently adopted and for the 10-inch rim which is recom- 

 mended for adoption. The radius of the fillet for the 3^, 4 and 

 414 straight-side rims has been increased from 3/32 to 3/16-inch 

 owing to trouble which has been experienced with rims cracking 

 at this point. Tolerances have also been placed upon the height 

 of the 3H-inch rim. 



