Midwest Industries, Inc. Ida Grove, IA 51445 800.859.3028 www.shorelandr.com 0003513
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When the tread has worn down to the point that they appear to
be even with the outside of the tread it is time to replace the tire.
Another method for checking tread depth is to place a penny in the
tread with Lincoln’s head upside down and facing you. If you can
see the top of Lincoln’s head, you are ready for new tires.
TIRE BALANCE AND WHEEL ALIGNMENT
To avoid vibration or shaking of the trailer when it is towed, the
tires must be properly balanced. Unbalanced tires, when rotate,
will cause vibration. The more they are out of balance, the more
the vibration will be. This vibration can be eliminated by positioning
weights on the wheel to counterbalance heavy spots on the wheel
and tire assembly. Most any tire store or service station that deals
with tires has the capability of balancing tires.
The wheels must be aligned so they are rotating in the same plane
as what the trailer is being towed. They must be positioned so that
they rotate in the same line as the trailer rather than at some slight
angle either inward or outward from this line. If they are not aligned
correctly, they will have a tendency to skid down the road caus-
ing the tread to wear off quickly and crooked. Correct alignment
maximizes the life of your tires and are preset when the axles are
welded during manufacturing. This alignment is correct and will
remain correct when towed under most towing conditions. Hitting
curbs and large pot holes with the trailer tires may distort the axle
and cause the spindle position to be knocked out of alignment.
TIRE REPAIR
The proper repair of a punctured tire requires a plug for the hole
and a patch for the area inside the tire that surrounds the puncture
hole. Punctures through the tread can be repaired if they are not
too large, but punctures to the side wall should not be repaired.
Tires must be removed from the rim to be properly inspected before
being plugged and patched.
TIRE FUNDAMENTALS
Federal law requires tire manufacturers to place standardized in-
formation on the side wall of all tires. This information identifies
and describes the fundamental characteristics of the tire and also
provides a tire identification number for safety standard certification
and in case of a recall.
INFORMATION ON PASSENGER VEHICLE TIRES
Please refer to the diagram below.
The “ST” indicates the tire is a special trailer tire.
The “LT” indicates the tire is a light truck tire.
NEXT NUMBER
This three-digit number gives the width in millimeters of the tire
from side wall edge to side wall edge. In general, the larger the
number, the wider the tire.
NEXT NUMBER
This two-digit number, known as the aspect ratio, gives the tire’s
ratio of height to width. Numbers of 70 or lower indicate a short side
wall for improved steering response and better overall handling on
dry pavement.
R
The “R” stands for radial. Radial ply construction of tires has been
the industry standard for the past 20 years. A “D” stands for bias
ply construction.
NEXT NUMBER
This two-digit number is the wheel or rim diameter in inches. If you
change your wheel size, you will have to purchase new tires to
match the new wheel diameter.
U.S. DOT TIRE IDENTIFICTION NUMBER
This begins with the letters “DOT” and indicates that the tire meets
all federal standards. The next two numbers or letters are the
plant code where it was manufactured, and the last four numbers
represent the week and year the tire was built. For example, the
numbers 3197 means the 31st. week of 1997. The other numbers
are marketing codes used at the manufacturer’s discretion. This
information is used to contact consumers if a tire defect requires
a recall.
TIRE PLY COMPOSITION AND MATERIALS USED
The number of plies indicates the number of layers of rubber-coat-
ed fabric in the tire. In general, the greater the number of plies, the
more weight a tire can support. Tire manufacturers also must indi-
cate the materials in the tire, which include steel, nylon, polyester,
and others.
MAXIMUM LOAD RATING
This number indicates the maximum load in kilograms and pounds
that can be carried by the tire.
MAXIMUM PERMISSIBLE INFLATION PRESSURE
The number is the greatest amount of air pressure that should ever
be put in the tire under normal driving conditions.
UTQGS (Uniform Tire Quality Grading System) INFORMATION
TREADWEAR NUMBER
This number indicates the tire’s wear rate. The higher the tread
wear number is, the longer it should take for the tread to wear
down. For example, a tire graded 400 should last twice as long as
a tire graded 200.
TRACTION LETTER
This letter indicates a tire’s ability to stop on wet pavement. A high-
er graded tire should allow you to stop your car on wet roads in a
shorter distance than a tire with a lower grade. Traction is graded
from highest to lowest as “AA”, “A”, “B”, and “C”.
TEMPERATURE LETTER
This letter indicates a tire’s resistance to heat. The temperature
grade is for a tire that is inflated properly and not overloaded. Ex-
cessive speed, under-inflation or excessive loading, either sepa-
rately or in combination, can cause heat build-up and possible tire
failure. From highest to lowest, a tire’s resistance to heat is graded
