Great Dane Champion CP Manuel d'entretien - Page 11

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tire care

continued

Running a tire under inflated can have serious

consequences in addition to reducing tread life. Heat

buildup can cause the tire body to deteriorate, resulting

in separation of the tread from the body or belt ply. A

soft tire overdeflects, causing fatigue breaks in the body

cords. Continued overdeflection causes breaks in the

body cord construction, leading to sudden air loss.

Running duals with one tire flat or severely under

inflated will lead to intense heat buildup in the flat or

low tire due to external and internal friction – to the

extent that the casing will likely burst into flames.

Also, one tire of a dual running flat or low means the

other is overloaded and may fail.

OVER INFLATION can also cause serious damage to

a tire. Because a tire is more rigid when over inflated, it

does not absorb road shocks as well. This can lead to

body breaks when impacting a bump or chuckhole.

It can stress the rim, leading to rim failure. And over

inflated tires are more likely to cut, snag, and puncture.

NOTICE:

Over inflation cannot increase the

carrying capacity of a tire above its maximum

rated load.

danger

Tires operated in a flat condition may catch fire

resulting in potential product and property loss.

PROPER MATCHING AND SPACING OF DUALS

Mismatched dual tires force the larger diameter tire to

an overload condition, causing it to overdeflect and

overheat. The smaller diameter tire will lack complete

road contact and will wear faster and more irregularly.

Tread or ply separation, tire body breaks, and blowouts

can develop from mismatching duals.

Permissible diameter differences between a tire and its

dual mate having equal inflation pressure are:

1/4" for 8.25 cross section (tubeless 9-22.5)

and smaller sizes

1/2" for 9.00 cross section (tubeless 10-22.5)

and larger sizes

To determine the difference in diameter measure the

tires forty-eight hours after initial inflation with a steel

tape. Measurements on the trailer can be made by

string gauge, straight edge, tire caliper, or a large

square.

Proper spacing between duals is necessary to prevent

sidewall contact at the "six o'clock" position. Such con-

tact creates excessive heat which can destroy the tires.

TIRE BRANDING

Whenever possible, tire branding should be in the

branding panel on the sidewall of most truck tires.

Use extreme caution to prevent branding too deeply.

The ideal branding depth is 1/32", and in no case

should it exceed 1/16".

If no branding panel is on the tire, brand the sidewall

midway between the rim flange and the tire's maximum

section width.

NOTICE:

Never brand in the critical sidewall

flexing area near the tire maximum section width

of a radial ply tire. Branding that is too deep or

in the wrong place on the tire can result in tire

failure. Consult the tire manufacturer for more

detailed instructions.

MIXING RADIAL AND BIAS-PLY TIRES

Radial tires and bias-ply tires differ considerably in their

cornering force characteristics and spring rates. The

best overall performance usually can be achieved by

using tires of the same size and construction on all

wheels. However, different types of tires can be used in

combination on tandem axle trailers and multiple-axle

trailers under certain conditions.

Never mix different tire sizes or tire construction on the

same axle. Bias or radial tires may be used on either

axle of two-axle trailers if the trailer has dual rear

wheels or is equipped with wide-base single tires.

TUBE AND FLAPS

FOR TUBE-TYPE RADIAL TIRES

Since the tube holds the air, the importance of the tube

in the satisfactory performance of the tire is obvious.

The flexing characteristics of a radial truck tire require a

special inner tube. Never use a tube that has not been

identified as being suitable for use with radial-ply tires.

Both tubes and tires must be the same size. For

example, a 10.00R20 tube must be used with a

10.00R20 tire, and the tube must be for a radial tire.

When using flaps, use radial flaps. Radial flaps are

manufactured especially for radial truck tires. For

correct flap size, check the tire manufacturer's

specifications. Always check for the correct

designation before installing a flap in a radial truck tire.

Note: Always use new radial tubes and flaps when

mounting new tube-type radial tires.

Replace any tire that has fabric exposed through the

tread or sidewall, or that has less than 2/32" tread

depth.

TIRE LOADS

Great Dane Trailers, as required by the safety

regulations of the National Highway Traffic Safety

Administration has assigned a Gross Axle Weight Rating

(GAWR) for each axle on the undercarriage. (See exam-

ple certification plate at right)

The GAWR and tire information shown on the vehicle

certification plate was applicable at the time the trailer

was manufactured. If the tires or other components of

the running gear have been changed or altered since

the trailer was manufactured, the GAWR may have

changed. This should be checked with Great Dane

Trailers Customer Service Department.

axle alignment

Improper axle alignment with the trailer frame will cause

excessive tire wear and trailer "dogtracking". In extreme

cases, depending on trailer length, the outer tire of the

curbside wheels may have little or no contact with the

road, causing the entire wheel load to be carried by the

inner tire. Also, trailers that "dogtrack" will not have

identical right and left turning characteristics, which

complicates driving in areas with narrow streets and

sharp turns. Even though Great Dane aligns every trail-

er's axles prior to delivery, we still recommend that axle

alignment be checked and corrected if needed on initial

in-service and again every 20,000 miles.

SINGLE-AXLE PROCEDURE

1. Remove any parts of the undercarriage that will

interfere with the tape when it is stretched between

the kingpin and the ends of the axle – or avoid

removing the parts by using a Sweeny pogo stick

or equivalent device. Remove outer wheel if disc

type, or tire and rim assembly if steel spoked, or

entire assembly – depending on the wheel equip-

ment on the trailer.

2. Level trailer to its normal road condition.

3. With the S-hook and steel tape, measure the

distance from the kingpin to the center of the end

of the axle on each side (measurements A and B

on the single-axle illustration). These measurements

must be within 1/8" of each other.

When aligning axles, suspension should be in a natural,

relaxed state, free of any "binds" before taking meas-

urements. To achieve this relaxed condition, make sure

the vehicle is unloaded. Then roll it back and forth on a

level floor. Avoid brake application including parking

brakes. Vehicle must be level from side to side as well

as from front to rear.

To inspect the axle alignment, measure the distance

from the kingpin to the trailer axle on each side (and

from axle to axle for tandem-axles) as specified below.

But first fabricate a rigid S-hook that can be hooked

over the kingpin and attach a steel tape to it.

TANDEM-AXLES PROCEDURE

1. With the tandem axles in their natural working

position, roll the trailer back and forth over a level

surface a few times to permit the connecting linkage

to position itself properly and center front and rear

wheel track.

2. Remove any parts of the undercarriage that will

interfere with the tape when it is stretched between

the kingpin and the ends of the front axle – or avoid

removing the parts by using a Sweeny pogo stick

or equivalent device. Remove outer wheel of this

axle if disc type, or tire and rim assembly if steel

spoked, or entire assembly – depending on the

wheel equipment on the trailer.

3. Level trailer to its normal road condition.

4. With the S-hook and steel tape, measure the dis-

tance from the kingpin to the center of the end of

the front axle on each side (measurements A and B

of the tandem-axles illustration).

These measurements must be

within 1/8" of each other.