TrailMax T-10-UR User manual

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Table of Contents
Section 1. Operation .................................................................................... 3
1.0 Introduction ................................................................................... 3
1.1 Purpose ........................................................................................ 3
1.2 Rating............................................................................................ 3
1.3 Design and Safety Factors ........................................................... 4
1.4 Vehicle Load and Handling Limits ................................................ 4
1.5 Reporting Safety Defects ............................................................. 7
1.6 Alert Symbols ................................................................................ 8
1.7 Pre-Trip Inspection........................................................................ 9
1.8 Hook-Up Procedures .................................................................. 10
1.9 Loading and Unloading .............................................................. 11
Trailers With Ramps ................................................................. 12
Trailers With Tilt Decks ............................................................. 12
A.0 Addendum - Tire Safety Information ................................................
Section 2. Maintenance .............................................................................. 13
2.0 Periodic Maintenance .................................................................. 13
2.1 Structural Components ............................................................... 14
Sub-Frame ................................................................................ 14
Deck ......................................................................................... 14
2.2 Sub-Assembly Components ....................................................... 14
Coupling .................................................................................... 14
Jack .......................................................................................... 15
Cushion Cylinder....................................................................... 15
Deck Latch ................................................................................ 15
Deck Hinge Assembly ............................................................... 15
2.3 Running Gear .............................................................................. 16
Suspension ............................................................................... 16
Hubs and Drums....................................................................... 16
Brake Drum Inspection ............................................................. 17
Bearing Inspection .................................................................... 17
Standard Bearing Lubrication .................................................... 18
E-Z Lube Bearing Lubrication .................................................... 18
Seal Inspection and Replacement ............................................ 19
Hub Reinstallation and Bearing Adjustment .............................. 19
2.4 Wheels and Tires ........................................................................ 20
Wheels...................................................................................... 20
Tires .......................................................................................... 22
Inflation Pressure ...................................................................... 22
Tire Wear Diagnostic Chart ...................................................... 23
2.5 Electrical ..................................................................................... 24
Harnesses and Lights ............................................................... 24
Junction Block ........................................................................... 24
Electrical Plug ........................................................................... 24
Contents
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2.6 Brake System (Common to Hydraulic and Electric) ................... 25
Brake Adjustment ...................................................................... 25
Brake Cleaning and Inspection ................................................. 26
Brake Lubrication ...................................................................... 26
2.7 Hydraulic Brake System .............................................................. 27
Operation .................................................................................. 27
Surge Actuator Maintenance ..................................................... 27
Corrosive Environment Warning ............................................... 28
Hydraulic Lines.......................................................................... 28
Hydraulic Brakes ....................................................................... 28
Brake System Bleeding ............................................................ 29
Hydraulic Brake System Troubleshooting Chart ....................... 31
2.8 Electric Brake System ................................................................ 31
Operation .................................................................................. 31
Using your Brakes Properly ...................................................... 32
Synchronization ........................................................................ 33
Controllers ................................................................................ 33
Magnets .................................................................................... 34
Electric Brake System Troubleshooting .................................... 35
Measuring Voltage ..................................................................... 35
Measuring Amperage ................................................................ 37
Electric Brake System Troubleshooting Chart .......................... 38
2.9 Pre-Storage Maintenance ............................................................ 40
2.10 Pre-Season Maintenance ............................................................ 41
Section 3. Parts .......................................................................................... 42
3.1 Structural Components ............................................................... 42
Miscellaneous Fasteners .......................................................... 42
Deck Surface ............................................................................ 44
3.2 Major Sub-Assemblies ................................................................ 45
Hammerblow Drop Leg Jack .................................................... 45
Couplers ................................................................................... 46
3.3 Running Gear .............................................................................. 48
Hydraulic Brake Components ................................................... 50
Electric Brake Components, 5K ............................................... 52
Axle End Components .............................................................. 54
3.4 Wheels and Tires ........................................................................ 55
3.5 Electrical ..................................................................................... 56
Harnesses and Lights ............................................................... 56
Electrical Plug ........................................................................... 58
Electric Brake Wiring ................................................................ 59
Electric Breakaway System ...................................................... 59
3.6 Hydraulic System ........................................................................ 60
Hydraulic Lines.......................................................................... 60
Model DA10 Surge Actuator ...................................................... 62
3.7 Tool Box ....................................................................................... 64
Section 4. Warranty Claim Procedure ....................................................... 65
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Section 1. Operation
1.0 Introduction
This section describes how trailers can have different operational characteristics
based on design, load configuration, gross weights, suspension characteristics, articu-
lation and extreme differences between loaded and unloaded weights.
Trailers have safe operating limits just as automobiles, airplanes, and other ve-
hicles. The interaction of the vehicle characteristics, maintenance, load, roadway,
weather, the skill of the driver and vehicle speed affect these limits. Knowledge of how
these factors affect the vehicle’s operating limits and utilization of defensive driving
techniques should result in safer driving.
1.1 Purpose
The purpose of this section is to describe how the vehicle characteristics, mainte-
nance, road conditions, and weather can affect trailer control and stability limits, and
how driver awareness and skill can help compensate for these factors. This knowledge
will assist you to safely enjoy the maximum utility and productivity from your trailer.
First and foremost, DO NOT operate the trailer until you have read and fully under-
stand this instruction and operating manual. It is also important that each and every
person who operates the trailer be given the opportunity to read this manual.
1.2 Rating
Gross Axle Weight Rating (GAWR) is the rated load-carrying capacity of an indi-
vidual axle and wheel assembly. It represents the load that may be steadily sustained
by the components in the system; i.e., tires, wheels, hubs, bearings, axles, brakes,
suspension, sub-frame, etc. with the GAWR limited by the component with the lowest
working rating. Consideration of environmental and operational factors may require the
manufacturer to reduce the nominal rating.
Gross Vehicle Weight Rating (GVWR) is the maximum rated combined weight of a
trailer and its payload (uniformly distributed) based on its structural capabilities.
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1.3 Design and Safety Factors
The safety factor is a ratio between the design stress imposed by the load sitting
static on the trailer and the minimum yield stress of the steel used in construction of
that trailer structure. For example, if the structure is built using 50,000 psi minimum
yield strength steel and the load sitting on it causes a stress level of 25,000 psi then a
2:1 safety factor would exist. THIS SAFETY FACTOR DOES NOT MEAN THAT THE
STRUCTURE CAN THEN BE USED TO CARRY TWICE THE RATED LOAD. Under
dynamic conditions, or as the trailer moves and encounters shocks, vibrations, twists
and other conditions that exist during transport, stress levels are elevated far beyond
those in the static situation.
Distributed Load is when a load is distributed evenly over the length of the trailer
deck. This would be considered as the ideal load scenario when fully loaded to rated
capacity.
Concentrated Load is one that is localized over a shorter than normal distance and
imposes greater stress in the concentrated load areas. Under these conditions, it is not
recommended to carry the full rated capacity of the trailer. Extreme concentrated appli-
cations may require additional support for the load.
1.4 Vehicle Load and Handling Limits
Vehicle handling limits can be greatly affected by the weight of a load, its place-
ment, the amount of weight distributed over the axles and whether or not the load is
secured properly.
Tow vehicle and trailer combinations are designed to provide maximum directional
control and roll stability within the constraints of highway size and weight limits. Any
combination can be rolled over by driving too fast around a curve, making too abrupt a
maneuver, or by leaving the roadway. Locking up the wheels on an axle can result in a
jackknife or trailer swing out.
One of the major contributing factors to vehicle rollover is high center of gravity on
tall loads. Extreme caution should be used in maneuvering a vehicle and trailer combi-
nation, or any unit that has a tall load. Positioning the load in a central side to side
location will enhance directional control, roll stability and braking.
You should be aware that trailers with a shorter wheel base are more prone to roll
during an abrupt lane change or quick reactions at the wheel. This tendency can be
made dramatically worse with a tall, high center of gravity load.
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Overloading a vehicle should never be permitted. Overloading results in tire blow-
outs, spring breakage, frame damage, diminished braking capacity, and will severely
alter the vehicle’s normal handling characteristics. All vehicles are designed with a
maximum load capability. To best utilize these vehicles in the safest manner the loads
as shown on the certificate label should not be exceeded.
Adequate tongue weight is required for trailers to tow correctly. Inadequate tongue
weight can cause a “whipping action” particularly in shorter wheel base trailers. Too
much tongue weight can overload tow vehicle hitch resulting in reduced steering load
and loss of steering control. Selecting the correct tow vehicle is crucial for the applica-
tion.
Always maintain enough braking and stopping distance. Erratic or unequal brake
action from side to side on either tow vehicle or trailer can cause handling problems in
braking situations. A balance between tow vehicle and trailer on brake application and
release timing and synchronized pressure will reduce push/pull characteristics which
when excessive, may result in jackknife. The use of properly matched brake lining is
recommended to enhance safer braking.
Proper alignment of both tow vehicle and trailer wheels will add significantly to the
handling characteristics of the combination and allow the driver to utilize all the design
responses of the vehicle to make evasive maneuvers in the safest manner.
Irregular terrain, steep grades and crowned roads, especially rural roadways, free-
ways, exit ramps, curves, bumps and depressions introduce forces into a tow vehicle/
trailer combination that could result in an accident if proper precautions and driving
techniques are not followed. Even a vehicle that meets all maintenance and load re-
quirements can become hazardous when excessive speeds and certain roadway char-
acteristics are combined.
While on a downgrade, the force of gravity works against the driver in maintaining
control of the vehicle, particularly if the road surface is wet or slick from snow and ice
or loose material. On upgrades, the problem is spinning out due to insufficient traction
at the drive wheels, particularly on snow and ice.
Great care must be taken to avoid excessive use of brakes on long downgrades.
Overheated brakes are dangerously inefficient. It is very dangerous to brake on a
downgrade using only the trailer brakes. If this is done, the trailer brakes heat up and
fade and the tow vehicle brakes alone will not be able to stop the combination by
themselves. Drivers should reduce speed, downshift and use engine compression as
the principal means of controlling speed on long grades and using all brakes so brake
temperatures can be held to a safe level.
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Operation
Weather conditions can be a major factor in the cause of accidents. Rain, ice, snow,
high winds and visibility combined with excessive speed, sudden lane changes, or
other factors that put lateral forces into a tow vehicle trailer combination contribute
significantly to an accident.
Slippery roads can increase stopping distances and reduce the ability to control the
vehicle. When the road is wet, the available tire/road friction may be half that of a dry
road, and icy roads can reduce friction many times over wet roads. If hard braking or
rapid acceleration occurs, there may be little or no friction available to prevent tire
lateral movement and skidding results.
The driver has a responsibility to compensate for the characteristics and conditions
of his vehicle, the road conditions and weather. Reducing speeds and increasing atten-
tiveness may compensate for most of these conditions. The more familiar the driver is
with the vehicle and the road, the less likely he will need to make abrupt emergency
maneuvers which will take the vehicle to its limits. Control and stability may be main-
tained if the driver knows his vehicle, his load, and the road.
Either braking or accelerating while cornering can significantly reduce the control-
lability and stability of the vehicle and should be avoided. The best driving practice is to
decelerate to a safe conservative speed before entering a corner or approaching con-
gested traffic and then apply only moderate power until an essentially straight path has
been established.
It is imperative that a safe speed always be maintained. The safe speed is that
speed at which control can be maintained over the vehicle at all times. This speed will
allow an emergency change of lane maneuver, travel off an exit ramp with a tightening
radius and recovery from pavement drop-off or wet pavement. This speed will vary from
one combination of vehicle to another and takes into consideration such factors as
road conditions, weather, traffic, visibility, type of load and experience of the driver.

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1.5 Reporting Safety Defects
If you believe that your vehicle has a defect that could cause a crash, injury, or death,
you should immediately inform the National Highway Traffic Safety Administration (NHTSA)
in addition to notifying Gem State Mfg., Inc.
If NHTSA receives similar complaints it may open an investigation, and if it finds that a
safety defect exists in a group of vehicles it may pursue a remedy campaign and recall
those vehicles. However, NHTSA cannot become involved in individual problems between
you, your dealer, or Gem State Mfg., Inc.
To contact NHTSA, you may either call the Vehicle Safety Hotline toll free at 1-888-327-
4236 (TTY: 1-800-424-9153), go to http://www.safecar.gov; or write to Administrator,
NHTSA, 400 Seventh Street SW., Washington, DC 20590. You can also obtain other
information about motor vehicle safety from http://www.safecar.gov.
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Operation
1.6 Alert Symbols
It is important that your know the meaning of the following symbols that are used
throughout this document.
SAFETY ALERT!
This is the safety alert symbol. It is used to alert you to potential per-
sonal injury hazards. Obey all safety messages that follow this symbol to
avoid possible injury or death.
DANGER!
DANGER! indicates an imminently hazardous situation which, if not
avoided, will result in death or serious injury.
WARNING!
WARNING indicates a potentially hazardous situation which, if not
avoided, could result in death or serious injury.
CAUTION!
CAUTION indicates a potentially hazardous situation which, if not
avoided, may result in minor or moderate injury.
CAUTION
CAUTION used without the safety alert symbol indicates a potentially
hazardous situation which, if not avoided, may result in property damage.
!
DANGER
!
WARNING
!
CAUTION
!
CAUTION

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1.7 Pre-Trip Inspection
There are some items on every vehicle combination that can be and should be
inspected prior to every trip that require no special knowledge, training, or sophisti-
cated equipment.
Before beginning a trip, make a thorough visual inspection of the trailer for cracks
in the structure, or bent components such as the tongue or frame. Check for any miss-
ing fasteners in suspension as well as other areas, and look for broken or bent springs
and spring hangers or otherwise damaged components.
Verify that the hitch on the tow vehicle is the correct size and configuration to fit the
trailer coupling. The hitch must be rated to meet or exceed the Gross Vehicle Weight
Rating (GVWR) of the trailer.
Check the hitch height of the trailer and compare it to the tow vehicle; it is very
important that the trailer be towed in the level position when loaded. In order to achieve
the correct hitch height, elevate the tongue of the trailer slightly (1" to 2") by adjusting
the trailer hitch to compensate for settling of tow vehicle springs when loaded.
Always visually inspect hitch for unusual appearances such as bent components,
cracks in welds or chipped paint where stress cracks may appear from high loads.
Check tires for proper inflation. Tire manufacturers recommend checking inflation
pressure while trailer is not loaded and tires are cool. This will provide a more accurate
reading. A drop of 10 PSI in tire pressure can reduce the carrying capacity of the tire as
much as 20%. This reduced capacity could cause tire failure and poor tire life.
Maintaining proper wheel nut torque value is essential to prevent wheel end sepa-
ration or potential damage to the hub or wheel. Always check wheel nuts every 50 to
100 miles for the first 200 miles of operation, then periodically thereafter. The same
procedure should be repeated after dismount and remount of wheels. It is important to
follow the specified tightening sequence recommended in the tire maintenance section
of this manual.
NOTE: For trailers with hydraulic surge brakes, check the brake fluid reservoir
level and add brake fluid to the fill line if necessary.
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1.8 Hook-Up Procedures
TRAILER HOOK-UP
The consequences of not properly hooking the trailer to the tow vehicle
can be very serious. Failure to adhere to information in this section could
lead to the trailer becoming detached, the trailer brakes and/or lights not
working correctly, or other unsafe situations which could result in an acci-
dent causing property damage, bodily injury or death.
Connect the tow vehicle to the trailer and check that the coupler is completely latched.
Be sure that a safety pin is inserted to ensure coupler will not unlatch during transport.
Connect the electrical plug from the trailer’s harness to the receptacle of the tow ve-
hicle. Check all lights on the trailer to make sure they are working correctly with the tow
vehicle’s electrical system.
Be sure the landing leg and drop foot are fully retracted and the crank handle is
stowed in transport position. For trailers with 2-speed jacks, use low gear for raising
and lower the jack under load, and high gear for raising and lowering the leg when it is
off the ground.
Check all safety chains and their attachment to both the trailer and the towing ve-
hicle. Connect safety chains to tow vehicle using crossed pattern under tongue. Allow
slack for turning, but avoid having chains drag on pavement. Make certain that all
attachment devices are properly installed and in good working order.
For trailers with air brakes, connect the Glad Hands (one service and one emer-
gency) to tow vehicle. Shut off petcock(s) on air tank(s) or if already shut, open to
exhaust all moisture, then shut off. It is very important that the air system be drained of
moisture after each use to keep all components functioning properly and to make equip-
ment safe.
Trailers with electric brakes or hydraulic surge brakes come equipped with an emer-
gency breakaway device. The breakaway system is designed to operate after the cou-
pling system has failed. Connect breakaway chain S-hook to bumper or hitch on tow
vehicle. Allow slack for turning, but avoid letting chain drag on pavement. Provide as
straight a connection as possible.
Always check that trailer brakes are working properly. If trailer is equipped with electric
brakes, use brake controller to adjust for load.
The breakaway system is for emergencies and is not a parking brake.
The following paragraphs pertain to trailers with hydraulic surge brakes:
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Operation
The ‘surge’ or ‘push’ of the trailer toward the tow vehicle when the tow vehicle brakes
are applied actuates the trailer brakes. Excessive surge actuator travel (over one inch)
when brakes are applied indicates a need to adjust the trailer brakes.
Should the breakaway be accidentally applied while unhitching, pry the breakaway
locks apart to release lever.
Sway control devices that restrict operation of the actuator cannot be used. The
actuator must be free to telescope in response to braking requirements.
1.9 Loading and Unloading
TRAILER LOADING PRACTICES
The consequences of ignoring proper trailer loading practices can be
very serious. Failure to adhere to the information in this section could
lead to unsafe handling, diminished braking capacity, or other unstable
trailer characteristics which could result in an accident causing property
damage, bodily injury or death.
It is the operators responsibility to take whatever steps necessary to load the
trailer properly, even when it is not easy to calculate the total load or determine the
load center of gravity.
A decal on the trailer similar to the one shown below indicates the correct placement of
the load. Load the trailer so that 60% of the total load weight is forward of the arrow, and
40% is rearward of the arrow. This will ensure that the proper load balance and tongue
weight are achieved.
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MAINTAIN 60% OF LOAD
FORWARD OF THIS POINT
(REFER TO OWNERS MANUAL)
ADVERSE WEATHER CONDITIONS!
Adverse weather conditions can cause wet and slippery trailer decks
and ramps. Depending on the type of equipment and typical weather con-
ditions it may be necessary to add traction aids to the trailer deck and
ramps.
CAUTION
!
CAUTION
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Always use extreme caution when loading and unloading equipment on trailer. Make
sure road surface is level. Loading and unloading on an uneven surface may cause dam-
age to the trailer frame and create unsafe loading conditions.
Always set brakes on tow vehicle and trailer before loading and unloading and use
chock blocks as an added safety precaution.
Before securing equipment, always lower booms, loaders and buckets. The parking
brake on the equipment being transported must be engaged, where applicable. Always
make sure you are under the maximum allowable height clearance.
Equipment with crawler tracks as well as wheel type equipment should be restrained
in the lateral, forward, rearward and vertical direction using a minimum of four direct
tie-downs and binders each having a working load limit of at least 5000 lbs. and should
be blocked to prevent forward movement.
Articulated vehicles shall be restrained in a manner that prevents articulation while
in transit.
Trailers With Ramps
Loading ramps can be adjusted for various track widths. Prior to loading or unload-
ing it is very important that ramps are adjusted to proper spacing for equipment being
transported. When loading equipment onto deck, drive slowly forward until appropriate
tongue load is achieved. Ramps are designed to support rear of trailer during loading
and unloading. Ramps must be in stored position during transport.
Trailers With Tilt Decks
It is very important that the deck latch is in the locked position with the safety pin
inserted at all times during transport. Always unlock deck when unloading equipment.
Failure to do this may result in damage to deck. Deck latch is adjustable to keep deck
tight and rattle free.
When loading equipment onto deck, drive slowly until deck begins to tilt closed, and
proceed forward until 10% of load weight in on the hitch of trailer. Not enough tongue
weight can result in swaying of trailer, which can be an unsafe condition.
When unloading use reverse procedure as loading. Back up slowly until deck begins to
tilt, stop and wait for deck to completely open, then proceed to back off slowly.
Trailer deck will tilt open and tilt closed with one persons weight. The deck may tilt
faster or slower depending on outside temperature, because the temperature affects
the density of the fluid in the deck cylinder.
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Addendum
Addendum
A. Tire Safety Information
If your trailer wieght less than 10,000 pounds GVWR or less, it will have a Tire and
Loading Information Placard. (See Below)
To Determine the correct load limit for your trailer complete the following steps:
1 - Locate the statement, “The weight of cargo should never exceed XXX kg or XXX
lbs., “ on your vehicle’s placard. See figure 1-1.
2 - This figure equals the available amount of cargo and luggage load capacity.
3 - Determine the combined weight of luggage and cargo being loaded on the
vehicle. That weight may not safetly exceed the availalbe cargo and luggage
load capacity.
The trailer’s placard refers to teh Tire Information Placard attached adjacent to ro
near the trailer’s VIN (Certification) label at teh left front of the trailer.

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Addendum
Addendum
A.1. Tire Safety - Everything Rides On It
The National Traffic Safety Administration (NHTSA) has published a brochure (DOT HS
809 361) that discusses all aspects of Tire Safety, as required by CFR 575.6. This
brochure is reproduced in part below. It can be obtained and downloaded from NHTSA,
free of charge, from the following web site:
http://www.nhtsa.dot.gov/cars/rules/TireSafety/ridesonit/tires_index.html
Studies of tire safety show that maintaining proper tire pressure, observing tire and
vehicle load limits (not carrying more weight in your vehicle than your tires or vehicle can
safely handle), avoiding road hazards, and inspecting tires for cuts, slashes, and other
irregularities are the most important things you can do to avoid tire failure, such as tread
separation or blowout and flat tires. These actions, along with other care and mainte-
nance activities, can also:
· Improve vehicle handling
· Help protect you and others from avoidable breakdowns and accidents
· Improve fuel economy
· Increase the life of your tires.
This booklet presents a comprehensive overview of tire safety, including information on
the following topics:
· Basic tire maintenance
· Uniform Tire Quality Grading System
· Fundamental characteristics of tires
· Tire safety tips.
Use this information to make tire safety a regular part of your vehicle maintenance
routine. Recognize that the time you spend is minimal compared with the inconvenience
and safety consequences of a flat tire or other tire failure.
A.2. Safety First - Basic Tire Maintenance
Properly maintained tires improve the steering, stopping, traction, and load-carrying
capability of your vehicle. Underinflated tires and overloaded vehicles are a major cause
of tire failure. Therefore, as mentioned above, to avoid flat tires and other types of tire
failure, you should maintain proper tire pressure, observe tire and vehicle load limits,
avoid road hazards, and regularly inspect your tires.

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Addendum
Addendum
A.3. Finding Your Vehicle’s Recommended Tire Pressure and Load Limits
Tire information placards and vehicle certification labels contain information on tires and
load limits. These labels indicate the vehicle manufacturer’s information including:
· Recommended tire size
· Recommended tire inflation pressure
· Vehicle capacity weight (VCW–the maximum occupant and cargo weight a vehicle is
designed to carry)
· Front and rear gross axle weight ratings (GAWR– the maximum weight the axle
systems are designed to carry).
Both placards and certification labels are permanently attached to the trailer near the left
front.
A.4. Understanding Tire Pressure and Load Limits
Tire inflation pressure is the level of air in the tire that provides it with load-carrying
capacity 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)–a tire requires to be properly inflated. (You will also find this number on the
vehicle information placard expressed in kilopascals (kPa), which is the metric measure
used internationally.)
Manufacturers of passenger vehicles and light trucks determine this number based on
the vehicle’s design load limit, that is, the greatest amount of weight a vehicle can safely
carry and the vehicle’s tire size. The proper tire pressure for your vehicle 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 manufac-
turers 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.
A.5. Checking Tire Pressure
It is important to check your vehicle’s tire pressure at least once a month for the following
reasons:
· Most tires may naturally lose air over time.

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· Tires can lose air suddenly if you drive over a pothole or other object or if you
strike the curb when parking.
· With radial tires, it is usually not possible to determine underinflation by visual
inspection.
For convenience, purchase a tire pressure gauge to keep in your vehicle. Gauges can
be purchased at tire dealerships, auto supply stores, and other retail outlets.
The recommended tire inflation pressure that vehicle manufacturers provide reflects the
proper psi when a tire is cold. The term cold does not relate to the outside temperature.
Rather, a cold tire is one that has not been driven on for at least three hours. When you
drive, your tires get warmer, causing the air pressure within them to increase. Therefore,
to get an accurate tire pressure reading, you must measure tire pressure when the tires
are cold or compensate for the extra pressure in warm tires.
A.6. Steps for Maintaining Proper Tire Pressure
· Step 1: Locate the recommended tire pressure on the vehicle’s tire information
placard, certification label, or in the owner’s manual.
· Step 2: Record the tire pressure of all tires.
· Step 3: If the tire pressure is too high in any of the tires, slowly release air by
gently pressing on the tire valve stem with the edge of your tire gauge until you get
to the correct pressure.
· Step 4: If the tire pressure is too low, note the difference between the measured
tire pressure and the correct tire pressure. These “missing” pounds of pressure
are what you will need to add.
· Step 5: At a service station, add the missing pounds of air pressure to each tire
that is underinflated.
· Step 6: Check all the tires to make sure they have the same air pressure (except
in cases in which the front and rear tires are supposed to have different amounts
of pressure).
If you have been driving your vehicle and think that a tire is underinflated, fill it to the
recommended cold inflation pressure indicated on your vehicle’s tire information placard
or certification label. While your tire may still be slightly underinflated due to the extra
pounds of pressure in the warm tire, it is safer to drive with air pressure that is slightly
lower than the vehicle manufacturer’s recommended cold inflation pressure than to drive
with a significantly underinflated tire. Since this is a temporary fix, don’t forget to recheck
and adjust the tire’s pressure when you can obtain a cold reading.
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Addendum
A.7. Tire Size
To maintain tire safety, purchase new tires that are the same size as the vehicle’s origi-
nal tires or another size recommended by the manufacturer. Look at the tire information
placard, the owner’s manual, or the sidewall of the tire you are replacing to find this
information. If you have any doubt about the correct size to choose, consult with the tire
dealer.
A.8. Tire Tread
The tire tread provides the gripping action and traction that prevent your vehicle from
slipping or sliding, especially when the road is wet or icy. In general, tires are not safe
and should be replaced when the tread is worn down to 1/16 of an inch. Tires have built-
in treadwear indicators that let you know when it is time to replace your tires. These
indicators are raised sections spaced intermittently in the bottom of the tread grooves.
When they appear “even” with the outside of the tread, it is time to replace your tires.
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.
A.9. Tire Balance and Wheel Alignment
To avoid vibration or shaking of the vehicle when a tire rotates, the tire must be properly
balanced. This balance is achieved by positioning weights on the wheel to counterbal-
ance heavy spots on the wheel-and-tire assembly. A wheel alignment adjusts the angles
of the wheels so that they are positioned correctly relative to the vehicle’s frame. This
adjustment maximizes the life of your tires. These adjustments require special equip-
ment and should be performed by a qualified technician.
A.10. 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 sidewall should not be repaired.
Tires must be removed from the rim to be properly inspected before being plugged and
patched.
A.11. Tire Fundalmentals
Federal law requires tire manufacturers to place standardized information on the
sidewall of all tires. This information identifies and describes the fundamental characteri-
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istics of the tire and also provides a tire identification number for safety standard certifi-
cation and in case of a recall.
A.11.1. Information on Passenger Vehicle Tires
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P
The “P” indicates the tire is for passenger vehicles.
Next number
This three-digit number gives the width in millimeters of the tire from sidewall edge to
sidewall 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 sidewall 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.
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.
Next number
This two- or three-digit number is the tire’s load index. It is a measurement of how much
weight each tire can support. You may find this information in your owner’s manual. If not,

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contact a local tire dealer. Note: You may not find this information on all tires because it
is not required by law.
M+S
The “M+S” or “M/S” indicates that the tire has some mud and snow capability. Most
radial tires have these markings; hence, they have some mud and snow capability.
Speed Rating
The speed rating denotes the speed at which a tire is designed to be driven for ex-
tended periods of time. The ratings range from 99 miles per hour (mph) to 186 mph.
These ratings are listed below. Note: You may not find this information on all tires be-
cause it is not required by law.
Letter Rating Speed Rating
Q 99 mph
R 106 mph
S 112 mph
T 118 mph
U 124 mph
H 130 mph
V 149 mph
W 168* mph
Y 186* mph
* For tires with a maximum speed capability over 149 mph, tire manufacturers some-
times use the letters ZR. For those with a maximum speed capability over 186 mph, tire
manufacturers always use the letters ZR.
U.S. DOT Tire Identification 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 num-
bers 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-coated fabric in the tire. In
general, the greater the number of plies, the more weight a tire can support. Tire manu-
facturers also must indicate the materials in the tire, which include steel, nylon, polyester,
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Maximum Load Rating
This number indicates the maximum load in kilograms and pounds that can be carried
by the tire.
Maximum Permissible Inflation Pressure
This number is the greatest amount of air pressure that should ever be put in the tire
under normal driving conditions.
A.11.2. UTQGS Information
Treadwear Number
This number indicates the tire’s wear rate. The higher the treadwear 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 higher 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. Excessive speed, underinflation or excessive
loading, either separately or in combination, can cause heat build-up and possible tire
failure. From highest to lowest, a tire’s resistance to heat is graded as “A”, “B”, or “C”.