18 BULLETIN NO. 770, U. S. DEPARTMENT OF AGRICULTURE 
TIRE EQUIPMENT. 
It is important that due consideration be given to the selection of 
tires, in view of the fact that tire cost is one of the heavy items in 
motor hauling. There are two general types of truck tires in use— 
the solid and the pneumatic. There is a third type, the cushion tire, 
which has a limited use at the present time, but by far the greater 
proportion of motor trucks are equipped with either solid or pneu- 
matic tires. The solid tire is more commonly used because it is more 
adaptable and cheaper than the pneumatic, does not suffer from blow- 
outs or punctures, and stands up well on bad roads and under very 
heavy loads. The pneumatic tire for truck use is a recent development, 
and there is less known about the possibilities of pneumatic tires for 
heavy loads than is known concerning the solid tires. Advocates of 
the pneumatic tire claim lessened vibration for truck and load, greater 
speed, and increased gasoline mileage. Where speed is essential, the 
pneumatic tire should be considered carefully. Where economy is the 
prime factor, the question is debatable. The majority of practical 
operators, however, favor the solid tire. No attempt will be made in 
this publication to issue an authoritative statement regarding the merits 
of the two types. 
The size of tires should depend upon two factors: (1) The weight 
of the ordinary load, and, (2) the character of the road. Under-size 
tires are not only uneconomical, but are injurious to the roads over 
which they travel. Over-size tires are initially expensive and, if the 
load is ordinarily light, are unnecessary. With slightly soft roads or 
extra heavy loads, over-size tires may be desirable. In general, the 
recommendations of the manufacturing company or its agents are 
more reliable than the judgment of an inexperienced operator. It is 
well for the prospective purchaser to consult local tire agencies in con- 
sidering new equipment. It should be remembered that the agent can 
offer authoritative advice only when he is fully informed as to operat- 
ing conditions, and when such advice is asked, the operator should 
state his case fully. 
DETERMINATION OF RATES. 
The Bureau of Markets has received many inquiries indicating that 
the question of a basis for the determination of motor freight or 
express rates is not clearly understood even by experienced operators. 
The operator of a regular commercial rural route (as distineuished 
from the farmer operating a truck for himself and a few of his 
neighbors) has little to guide him except the rates of other operators. 
As a rule, these are not sufficiently uniform to form an adequate or 
just basis of comparison. Many operators have established their rates 
on the basis of “what the traffic will bear.” Naturally, rates so 
established have varied in different localities and for different com- 
