Outdoors RV Mountain Series Owner's Manual page 30

On the Road
 117/112 - This is the 'Load Index' rating. A numerical code associated with the maximum load a
tire can carry at the speed indicated by its speed symbol (rating) under specified service
conditions. In this instance 117=2833lbs. You will not need to be concerned with the 112 as it
refers to loading in a dual wheel configuration.
 N - This is the tires 'Speed Rating'. An indexed alphabetical code that refers to the maximum
speed that a tire is rated by the tire manufacturer. In this instance N=87mph.
 Load Range 'E'- An alphabetic code that designates for a specific tire size the maximum load a
tire can carry at a defined inflation pressure.
Additional information you may find on your tires:
 US DOT - Tire Identification Number (TIN) - This begins with the letters DOT and indicates
that the tire meets 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 made. For
example, the numbers 3197 means the 31st week of 1997. The other numbers are marketing
codes used at the manufacturers' discretion. This information is used to contact consumers if a
tire defect requires a recall.
 Tire Ply Composition & Materials - The number of plies indicates the number of layers of
rubber coated fabric in the tire. In general, the greater the number of plies, the more weight a tire
can support. Tire manufacturers also must indicate the materials in the tire, which may include
steel, nylon, polyester, and others.
 Treadwear, Traction, & Temperature Grades - These numbers are a numeric index guide to
help the consumer make an informed decision in choosing replacement tires. These ratings are
not typically found on trailer service type tires and will not be explained in detail here.
 Load Limit & Maximum Cold Inflation - This is the designated maximum load limit that the
tire was designed to carry measured in lbs. & kg. based on a maximum cold air pressure
measured in psi and kPa. The listed pressure is the maximum air pressure that should ever be put
in the tire under normal driving conditions.
Additionally, you will find on (LT) & (ST) tires a (Max. Load Single) and (Max. Load Dual)
weight/pressure rating listed. The (Max. Load Dual) is used when running four wheels/tires per axle in
a 'dually' configuration such as that seen on a semi-truck. The Max. Load Dual application does not
apply to your RV.
Tire Pressure and Load Limits
Tire inflation pressure is the level of air in the tire that provides it with load-carrying capacity listed on
the tire sidewall and affects the overall performance of the vehicle. The tire inflation pressure is a
number that indicates the amount of air pressure measured in pounds per square inch (psi) or kilo Pascal
(kPa - metric) in which a tire requires to be properly inflated. RV manufacturers determine this number
based on the vehicles designed load limit, that is, the greatest amount of weight a vehicle can safely
carry for the vehicles tire rating. The proper tire pressure for your RV is referred to as the
'Recommended Cold Inflation Pressure' (As you will read below, it is difficult to obtain the
recommended tire pressure if your tires are not cold). Because tires are designed to be used on more than
one type of vehicle, tire manufacturers list the 'maximum permissible inflation pressure' on the tire
sidewall. This number is the greatest amount of air pressure that should ever be put in the tire under
normal driving conditions.
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