No. 6. 



DEPARTMENT OF AGRICULTURE. 



989 



(c) Clay road, dry, hard, ruts almost entirely obliterated; surface 

 worn smooth. Trial made November 20, 1896. Length of run, 400 

 feet. 



Average draft. 



Narrow tires, 130. G pounds. 



Broad tires, 76.2 " 



Difference in favor of broad tires, 54.4 " 



Percentage difference, in favor of broad 



. tires, 71.4 



Essentially the same conditions are met in these trials as were 

 presented in the tests on macadam and gravel roads and the general 

 results are the same. The broad tired wheels materially lessened 

 the draft in all runs. 



It will be observed that the draft is almost as light on the dirt 

 road in this condition as on the macadam road in its best condition 

 and is really less than on the gravel road in any condition in which 

 tests were made. 



On the dry dirt road the draft required to haul a 2,000 pound 

 load with narrow tired wheels was capable of drawing 2,620 pounds 

 in the first trial, 2,440 pounds in the second trial, 3,428 pounds in 

 the third trial, and 2,829 pounds as an average of the three trials 

 on the broad tired wiieels. 



(d) Dust 2 to 3 inches deep on the surface, very dry and loose, 

 underlaid by hard smooth roadbed. Trials made September 15, 1897. 

 Length of run, 300 feet and return. 



(e) Clay road. Surface sticky, firm underneath. Fair hauling 

 condition. Euts 4 to 6 inches deep with walls and bottom hard and 

 dry. First run made with narrow tires in original ruts. Broad tires 

 run over narrow ruts. Length of run, 400 feet. Trial made January 

 9, 1897. 



