No. 6 DEPARTMENT OF AGRICULTURE. 99U 



bearing surface of the wheel is large these roots tend to keep the 

 wheel on the surface, prevent ruts being cut, and therefore materially 

 reduce the draft. This is also true to a less degree of a surface cov- 

 ered with loose grass or other rubbish. 



The dillerence in draft in favor of the broad tires in the runs 

 on bluegrass sod varies from 26.5 per cent, on a hard, dry, smooth 

 surface to 8t).7 per cent, on a soft surface. Averaging all the trials 

 on pasture lands, we find a saving in draft amounting to 116.4 

 pounds, or 45.7 per cent, due to the broad tires. Therefore, with 

 the same effort required to draw one ton on the narrow tires over 

 pasture land in these trials, a load of 2,914 pounds could have been 

 drawn on the six inch tires. 



VI. Stubble Land. 



(a) Grown in cow peas the previous year; ground soft. Narrow 

 tires cut ruts 14 inches deep first run. Broad tires cut rut about 3 

 to 4 inches deep. Four horses were required to pull the narrow tired 

 wagon. Length of run, 400 feet. Trial made February 8, 1896. 



Average draft. 



Narrow tires, 758. 1 pounds. 



Broad tires, 538.7 " 



Difference in favor of broad tires, 219.4 " 



Percentage difference, 40 



(b) Wheat stubble. Dry, smooth and comparatively free from 

 weeds. Neither set of wheels made appreciable ruts. Length of 

 run, 400 feet. Trial made September 12, 1896. 



Average draft. 



Narrow tires, 298.5 pounds. 



Broad tires, 222 



Difference in favor of broad tires, 76.5 " 



Percentage difference, 34.4 



(c) Corn stubble free from weeds, nearly dry enough to plow. Sur- 

 face smooth and nearly level. Length of run, 400 feet. Trial made 

 March 27, 1896. 



Average draft. 



Narrow tires, 484.2 pounds. 



Broad tires, 325.7 " 



Difference in favor of broad tires, 158.5 " 



Percentage difference, 48 



(d) Corn stubble, game as "(c)." Draft record taken on the 14th 

 run in same ruts, each set of wheels being run on its own track. 

 Depth of rut: narrow tires 7 to 12 inches; broad tires 2 to 3-^ inches. 

 Length of run, 400 feet. Trial made March 27, 1896. 



