Midland SIDE DUMP GRAVEL TRAILER Operator's Manual page 70

5.2.7 TIRES (cont'd)
2. Tire Matching and Spacing on Duals
Tires on a dual assembly must be matched
for size (diameter or rolling radius) and type of
construction to obtain the desired and expected
performance and life.
a. Matching of Size:
Tire sizes can vary between manufacturers
and as they wear. Special care must be
taken to be sure the tire size (rolling radius,
diameter or circumference) is within the
following dimensions:
Rolling radius: 1/8 inch (3 mm)
Diameter:
Circumference: 3/4 inch (19 mm)
Measure the tire when it is mounted, inflated
to its specified pressure and not loaded.
The easiest method is to use a steel tape to
measure the circumference of the tire.
Unequal sized tires will require the larger
tire to carry more of the load and potentially
overload it. Overloading accelerates the
wear and can lead to tire failure. When the
one tire fails, the remaining tire or tires will
then also be overloaded. The smaller tire will
not contact the road surface properly and
will wear in an irregular manner giving poor
durability.
b. Tire Construction:
Customers can use radial or bias ply
tires on their trailer. However, it is
recommended that different types of tires
not be mixed on an axle. Each type of
tire has different deflection, cornering and
spring characteristics. These differing
characteristics cause the tires to always fight
each other during operation and will give
erratic handling and poor wear characteristics
when mounted on the same axle. Different
types can be mounted on different axles but
not on the same axle.
58
1/4 inch (6 mm)
Fig. 54 TIRE DIMENSIONS
c. Tire Spacing:
A wide variety of rims can be used on the
trailer and each will provide a different offset.
Select the rims to provide sufficient space
and clearance between the sidewalls of
the tires. Normally there should be at least
2 inches (50 mm) and 3 inches (75 mm)
between the sidewall of a bias ply and radial
dual tire assembly respectively. This spacing
will provide sufficient clearance for each type
of tire to deflect as they rotate and when
they impact a pothole or bump in the road. If
they touch during operation, they will wear
or abrade at the contact point. In addition,
tires that are too close do not shed dirt, trash
or stones that can get between them during
operation as well as properly spaced tires.
ROLLING RADIUS