4) 
From the curves shown on these figures the following conclusions 
may be drawn for well-constructed dry earth roads: 
| With a gross load of 5,000 pounds the unit draft decreases with 
_ the width of tire up to oud including the 5-inch width. 
_ The unit draft decreases directly as the weight per inch width of 
q Be ched, as shown by the fact that the curve in figure 6 is prac- 
i tically a straight line. 
The fact that the draft for a 6-inch tire is larger than that for a 
AS. inch, in all cases shown, merely indicates that there is no advan- 
Pe 
ana oo ee 
aun ane nna aoe | 
CEE ee 
Fic. 6.—Showing that the unit draft decreases directly as the weight per inch width of 
4 tire decreases. 
if there may be a  ccnegimiasens Im so oui 
; It is not advisable to exceed in any vehicle a unit weight per inch 
of width of tire in excess of that possessed by a standard road 
{ RECOMMENDATIONS. 
| While there has been in the past, and to a certain extent still is 
Kt to-day, wide variation in sizes and types of wagons marketed by the 
different manufacturers, it is believed that five sizes of wagons will 
2 be sufficient to meet all the needs of farming operations and all gen- 
pe al work except the heaviest trucking and certain specialized haul- 
. 
| 
