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3. Tire Safety Information
This portion of the User's Manual contains tire safety
information as required by 49 CFR 575.6.
Section 3.1 contains "Trailer Tire Information".
Section 3.2 contains "Steps for Determining Correct
Load Limit - Trailer".
Section 3.3 contains "Steps for Determining Correct
Load Limit – Tow Vehicle".
Section 3.4 contains a Glossary of Tire Terminology,
including "cold infl ation pressure", "maximum infl ation
pressure", "recommended infl ation pressure", and
other non-technical terms.
Section 3.5 contains information from the NHTSA
brochure entitled "Tire Safety – Everything Rides On
It".
This brochure, as well as preceding subsections,
describes the following items;
• Tire labeling, including a description and explanation
of each marking on the tires, and information about
the DOT Tire Identifi cation Number (TIN).
• Recommended tire infl ation pressure, including a
description and explanation of:
A. Cold infl ation pressure.
B. Vehicle Placard and location on the vehicle.
C. Adverse safety consequences of under infl ation
(including tire failure).
D. Measuring and adjusting air pressure for proper
infl ation.
• Tire Care, including maintenance and safety
practices.
• Vehicle load limits, including a description and
explanation of the following items:
A. Locating and understanding the load limit
information, total load capacity, and cargo
capacity.
B. Calculating total and cargo capacities with
varying seating confi gurations including
quantitative examples showing / illustrating
how the vehicles cargo and luggage capacity
decreases as combined number and size
of occupants' increases. This item is also
discussed in Section 3.
C. Determining compatibility of tire and vehicle load
capabilities.
D. Adverse safety consequences of overloading on
handling and stopping on tires.
Tire Safety
3.1 Trailer Tire Information
Trailer tires may be worn out even though they still
have plenty of tread left. This is because trailer tires
have to carry a lot of weight all the time, even when
not in use.
It is actually better for the tire to be rolling down the
road than to be idle. During use, the tire releases
lubricants that are benefi cial to tire life. Using the
trailer tires often also helps prevent fl at spots from
developing.
The main cause of tire failure is improper infl ation.
Check the cold tire infl ation pressures at least once a
week for proper infl ation levels. "Cold" means that the
tires are at the same temperature as the surrounding
air, such as when the vehicle has been parked
overnight. Wheel and tire manufacturers recommend
adjusting the air pressure to the trailer manufacturer's
recommended cold infl ation pressure, in pounds per
square inch (PSI) stated on the vehicle's Federal
Certifi cation Label or Tire Placard when the trailer is
loaded to its gross vehicle weight rating (GVWR).
If the tires are infl ated to less than the recommended
infl ation level or the GVWR of the trailer is exceeded,
the load carrying capacity of the tire could be
dramatically affected. If the tires are infl ated more
than the recommended infl ation level, handling
characteristics of the tow vehicle/trailer combination
could be affected. Refer to the owner's manual or talk
to your dealer or vehicle manufacturer if you have any
questions regarding proper infl ation practices.
Tires can lose air over a period of time. In fact, tires
can lose 1 to 3 PSI per month. This is because
molecules of air, under pressure, weave their way
from the inside of the tire, through the rubber, to the
outside. A drop in tire pressure could cause the tire to
become overloaded, leading to excessive heat build
up. If a trailer tire is under-infl ated, even for a short
period of time, the tire could suffer internal damage.
High speed towing in hot conditions degrades trailer
tires signifi cantly. As heat builds up during driving,
the tire's internal structure starts to breakdown,
compromising the strength of the tire. It is
recommended to drive at moderate speeds.
Statistics indicate the average life of a trailer tire is
about fi ve years under normal use and maintenance
conditions. After three years, replacing the trailer
tires with new ones should be considered, even if the
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