characteristics.

Suspensions

The Airflex® suspension air generation kit has a built in dump valve which allows
the trailer to be lowered several inches to facilitate loading or leveling. Once
loaded, the valve is reversed and the system is pressurized to raise the trailer
back up to normal running height.
Axle Adjustment
1. Support the trailer frame on a level surface. If the wheels are already
mounted, make sure they are clear of the ground. If the air actuation
system has been installed, make sure the air pressure in the air bags is
bled off before lifting the trailer.

-70-

!

CAUTION

Do not lift or support the trailer on any part of the axle or suspension
system. Never go under any trailer unless it is properly supported on
jack stands which have been rated for the load. Improperly supported
vehicles can fall unexpectedly and cause serious injury or death.
2. Measure from king pin to spindle center on each side. To simplify this
process, plumb lines may be dropped from the king pin and from the
center line of each spindle end. Measurements “A” and “B” can then be
taped on the floor to eliminate any miss measurement due to sagging of
the tape for long measurements. Compare A and B measurements (see
Figure 1).
3. Suspension front pivot connection is torqued to 270 Ft. Lbs. when the
suspension is shipped. The axle should be aligned on the trailer in this
condition.

-71-

Suspensions

Note: Lifting the trailer with air system pressurized will overextend the air
bags and can result in damage to the air bags.

Wheels
Wheel Selection
Wheels are a very important and critical component of your running gear
system. When specifying or replacing your trailer wheels it is important that
the wheels, tires, and axle are properly matched. The following characteristics
are extremely important and should be thoroughly checked when replacement
wheels are considered.
1. Bolt Circle. Many bolt circle dimensions are available. Some vary by so
little that it might be possible to attach an improper wheel that does not
match the axle hub. Be sure to match your wheel to the axle hub.
2. Capacity. Make sure that the wheels have enough load carrying capacity
and pressure rating to match the maximum load of the tire and trailer.
3. Offset. This refers to the relationship of the center line of the tire to the
hub face of the axle. Care should be taken to match any replacement
wheel with the same offset wheel as originally equipped. Failure to
match offset can result in reducing the load carrying capacity of your
axle.
4. Rim Contour.

!

CAUTION

Wheels and Tires

Replacement tires must meet the same specifications as the
originals. Mismatched tires and rims may come apart with explosive
force and cause personal injury to yourself or others. Mismatched
tires and rims can also blow out and cause you to lose control and
have an accident which can result in serious injury or death.

-72-

CAUTION

Do not attempt to repair or modify a damaged wheel. Even minor
modifications can cause a dangerous failure of the wheel and result
in personal injury or death.

Torque Requirements
In June of 2004, Dexter ceased production of trailer wheels. If your vehicle is
equipped with Dexter steel wheels manufactured before that date, the following
wheel torque information will be applicable.
If your trailer is equipped with wheels produced by other manufacturers, you
must consult with the vehicle manufacturer to determine the appropriate torque
level for your wheels. However, you must not exceed the limits of the wheel
mounting studs on the axles.
It is extremely important to apply and maintain proper wheel mounting torque
on your trailer axle. Torque is a measure of the amount of tightening applied to
a fastener (nut or bolt) and is expressed as length force. For example, a force of
90 pounds applied at the end of a wrench one foot long will yield 90 Ft. Lbs.
of torque. Torque wrenches are the best method to assure the proper amount of
torque is being applied to a fastener.

!

CAUTION

Wheel nuts or bolts must be tightened and maintained at the proper
torque levels to prevent loose wheels, broken studs, and possible
dangerous separation of wheels from your axle, which can lead to an
accident, personal injuries or death.
Be sure to use only the fasteners matched to the cone angle of your wheel
(usually 60° or 90°). The proper procedure for attaching your wheels is as
follows:
1. Start all bolts or nuts by hand to prevent cross threading.
2. Tighten bolts or nuts in the sequence shown for Wheel Torque
Requirements.

-73-

Wheels and Tires

!

3. The tightening of the fasteners should be done in stages. Following
the recommended sequence, tighten fasteners per wheel torque
requirements diagram.
4. Wheel nuts/bolts should be torqued before first road use and after each
wheel removal. Check and re-torque after the first 10 miles, 25 miles,
and again at 50 miles. Check periodically thereafter.

Wheels and Tires

Wheel Torque Requirements
Wheel Installation Torque Sequence (Ft. Lbs.)
Wheel
Stud
1st
2nd
Final
Size
Size
Stage Stage
Torque

Cone Nut
Degree

12" - 440 BC

1/2"-20

20-25

35-40

60-75

60° Cone Nut

12" - 545 BC

1/2"-20

20-25

35-40

60-75

60° Cone Nut

13" - 440 BC

1/2"-20

20-25

35-40

60-75

60° Cone Nut

13" - 545 BC

1/2"-20

20-25

35-40

60-75

60° Cone Nut

14" - 545 BC

1/2"-20

20-25

50-60

100-120

60° Cone Nut

15" - 545 BC

1/2"-20

20-25

50-60

100-120

60° Cone Nut

15" - 655 BC

1/2"-20

20-25

50-60

100-120

60° Cone Nut

16" - 655 BC

1/2"-20

20-25

50-60

100-120

60° Cone Nut

16" - 865 BC

9/16"-18

20-25

50-60

140-170

60° Cone Nut

16.5" - 655 BC

1/2"-20

20-25

50-60

100-120

60° Cone Nut

16.5" - 865 BC

9/16"-18

20-25

50-60

140-170

60° Cone Nut

16.5" x 9.75"
865 BC

5/8"-18

50-60

120-125

175-225

Special Stud Piloted
With 90° Cone
Nuts

17.5" Hub Pilot
865 BC

5/8"-18

50-60

100-120

190-210

Hub Piloted With
Clamp Ring. 90°
Cone Nuts &
Greased Threads

17.5" Hub Pilot
865 BC

5/8"-18

50-60

90-200

275-325

Hub Piloted With
Flange Nut

17.5" Hub Pilot
865 BC

5/8"-18

50-60

60-110

150-175

Hub Piloted With
Swivel Flange Nut

-74-

TORQUE SEQUENCE
1
3

4
4

1

1
6

3

6

3

7

8

3
2

2

4 BOLT

5

5 BOLT

4

5

5

4

2

2

6 BOLT

8 BOLT

Maximum Wheel Fastener Torque
The wheel mounting studs used on Dexter axles conform to the SAE standards
for grade 8. The maximum torque level that can be safely applied to these studs
is listed in the following chart:

Stud Size

Maximum Torque

1/2"-20 UNF, class 2A
9/16"-18 UNF, class 2A
5/8"-18 UNF, class 2A

120 Ft. Lbs.
170 Ft. Lbs.
325 Ft. Lbs.

!

CAUTION

Exceeding the above listed torque limits can damage studs and/or
nuts and lead to eventual fractures and dangerous wheel separation.

CAUTION
Dexter’s patented Torq-N-Go™ swiveling wheel nut generates
significantly more clamp load than standard wheel nuts. Do not
exceed the specified torque or the wheel and/or stud may be
damaged. Special caution should be observed with steel wheels.
Some steel center discs may not be able to withstand the Torq-N-Go™
wheel nuts’ specified operating torque. It is the responsibility of the
trailer manufacturer to assure that its’ wheels are compatible with
this wheel nut.

-75-

Wheels and Tires

1

Tires
Before mounting tires onto the wheels, make certain that the rim size and
contour is approved for the tire as shown in the Tire and Rim Association
Yearbook or the tire manufacturers catalog. Also make sure the tire will carry the
rated load. If the load is not equal on all tires due to trailer weight distribution,
use the tire rated for the heaviest wheel position.
Note: The capacity rating molded into the sidewall of the tire is not always
the proper rating for the tire if used in a trailer application. Use the following
guidelines:
1. LT and ST tires. Use the capacity rating molded into the tire.
2. Passenger Car Tires. Use the capacity rating molded into the tire sidewall
divided by 1.10 for trailer use.
Use tire mounting procedures as outlined by the Rubber Manufacturer’s
Association or the tire manufacturers.
Tire inflation pressure is the most important factor in tire life. Inflation pressure
should be as recommended by the manufacturer for the load. Pressure should
be checked cold before operation. Do not bleed air from tires when they are hot.
Check inflation pressure weekly during use to ensure the maximum tire life and
tread wear. The following tire wear diagnostic chart will help you pinpoint the
causes and solutions of tire wear problems.

Wheels and Tires

CAUTION
Proper matching of the tire/wheel combination is essential to
proper function of your trailer running gear. Some tires may call for a
maximum inflation pressure above the rim or wheel capacity. DO NOT
EXCEED MAXIMUM INFLATION PRESSURES FOR RIMS OR WHEELS.
Catastrophic failure may result.

-76-

Wear Pattern

Cause

Action

Center Wear

Over Inflation

Adjust pressure to
particular load per tire
catalog

Edge Wear

Under Inflation

Adjust pressure to
particular load per tire
catalog

Side Wear

Loss of camber or
overloading

Make sure load doesn’t
exceed axle rating. Align
at alignment shop

Toe Wear

Incorrect toe-in

Align at alignment shop

Cupping

Out-of-balance

Check bearing adjustment
and balance tires

Flat Spots

Wheel lockup &
tire skidding

Avoid sudden stops when
possible and adjust
brakes

CAUTION
Tire wear should be checked frequently. Once a wear pattern
becomes firmly established in a tire it is difficult to stop, even if the
underlying cause is corrected.

-77-

Wheels and Tires

Tire Wear Diagnostic Chart

Replacement Parts/Kits
Electric Brake Magnets
Magnet Kit Number

Nut Torque
(Ft. Lbs.)
Brake Mounting

(one magnet per kit)

Wire
Color

7" x 1 1/4"

K71-057-00

White

45-70

10" x 1 1/2"