Kymco MO D50 Service Manual - chap 20 (pneumatici)

20. HIGH-SPEED TIRE

20-0

20

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HIGH-SPEED TIRE (TUBELESS TIRE)

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HIGH-SPEED TIRE CONSTRUCTION & FEATURES ------------ 20- 2
HIGH-SPEED TIRE MAINTENANCE PRECAUTIONS ----------- 20- 4
HIGH-SPEED TIRE REMOVAL/INSTALLATION ---------------- 20- 5
HIGH-SPEED TIRE REPAIR------------------------------------------ 20-16

20

20. HIGH-SPEED TIRE

20-1

HIGH-SPEED TIRE CON­STRUCTION & FEATURES

CONSTRUCTION

INNER LINER

A layer of rubber (inner liner) which
replaces the inner tube is stuck to the
inside wall of the high-speed tire. The
inner liner is made of thick rubber, a
material that high-pressure air can not
pass through. The liner can not be
lengthened like other inner tubes, so
when nails are inserted into the tire,
breaks will not be enlarged because
the nails are suppressed to avoid air
leaks. When tire break occurs, the
inserted nails will spring out to make
the tire run under low pressure. It is
very dangerous because the tire
temperature will raise highly to make
tire wobble during riding. Therefore,
riders must be very careful to check
tire pressure and inserted nails before
riding at high-speed.

•Tire pressure

•Tire deformation and damage

•Tire groove depth and abnormal

wear
Tire Depth: Front : 0.8mm

Rear : 0.8mm

•Imbedded metals, stones, or other

foreign matters

The bead base where tire and rim
contact is wrapped by rubber fabrics
called tire bead in order to reinforce
its function. The fabrics is specially
adopted for the high-speed tire to
keep its air density because air can
not pass through this material. Also,
the fabrics can keep the tire from
damage when the tire falls off, and
protect tire from damage due to
friction of wheel rim while riding.

Inner Tube

Tire Bead

Tube Valve

Tube Tire

Tread

Tire Flange

Circle Boundary

Tire Shoulder

Circle Boundary

Tire Flange

Tubeless Tire

Inner Liner

Tire Bead

Tread

Tire Valve

Tire Shoulder

20. HIGH-SPEED TIRE

20-2

TIRE FLANGE BEVEL ANGEL

If the tire flange radius is smaller than the
wheel rim radius, the tire and wheel can be
locked tightly. Take the advantage of tire
bead bevel angle to enlarge tire bead so
that the tire and rim can combine with
each other precisely. Consequently, it
can prevent air leaks and tire will not fall
off the rim when tire break or low
pressure occurs.

METHOD TO IDENTIFY A HIGH­SPEED TIRE

For distinguishing a high-speed tire from a
tube-tire, the word “TUBELESS” is
stamped on the side wall of the high­speed tire. A tire without this word
cannot be used as a high-speed tire.

RIM USED FOR HIGH-SPEED TIRE

For the purpose of preventing tire from
falling off the wheel rim while driving,
there are special requirements on the size,
shape and pressure density of rim used
for high-speed tire. It is necessary to use
special rims.
Refer to the Figure shown for distinction.
Air leaks occur easily when the wheel rim
is deformed. Avoid driving on rugged road
and crashing against stones.
When replacing the high-speed tire, also
replace the valve as a set.

• When replacing the high-speed tire,

use a tire of the same specification.

＊

Rim Used for High-speed Tire

Tire flange bevel angle is
larger than rim bevel angle
Tire Shape

TUBELESS

Rim Shape

Locked

Mark of
TUBELESS

Rim Valve

20. HIGH-SPEED TIRE

20-3

RIM VALVE USED FOR HIGH­SPEED TIRE

Air-tight valve is specially designed
for rim valve of a high-speed tire.

AIR-TIGHT VALVE
A rubber of special shape is used to

cover around the valve hole. The
spring of rubber can prevent air leaks.
Install the valve from the inner side of
the rim and then pull it out through
the rim valve hole with a special tool.

HIGH-SPEED TIRE FEATURES

•Air will not release quickly when a

nail is inserted into the tire. It is the
same as the tube-tire that tire break
may occur to a high-speed tire when
nails or other objects are inserted
into it. However, when a nail is
inserted into a high-speed tire,
external rubber and internal anti-leak
rubber will grip the nail tightly to
prevent air leaks. If the nail is deeply
inserted, air will not release quickly
to avoid sudden slipping of steering
handlebar.

•EXCELLENT COOLING

PERFORMANCE
Because the high-speed tire is

tubeless, the air within the tire will
contact the rim directly. Heat
produced during driving can be
dissipated through the rim. Heat
affects the rubber greatly and if the
tire temperature is not high, the tire
service life can be prolonged .

• Use only the KYMCO

recommended air-tight valve.

＊

There is no air leak when a nail is
inserted into the tire.

20. HIGH-SPEED TIRE

20-4



PRECAUTIONS FOR HIGH SPEED
TIRE STORAGE

STORAGE METHODS

If the space within the tire bead of a
high-speed tire is narrower than the
width of its rim, it is hard to install
the tire to the rim and pump air into
the tire. Therefore, it is better to put
cardboard within the tire bead and
put tires in order.
Tires deform easily if they are piled
horizontally. Avoid doing so.
As to the reused tires, the structure
of the rim remains the same. Install
the valve cap when the tire pressure
is lowered to 1/2 of the specified
pressure.

PLACE FOR STORAGE

The place used for storage should
avoid the following conditions:

A place where produces

ozone (a place near motors
or chargers)

A place with oils or

lubricants (especially in
service working area)

A place where produces

heat (a place near stoves
or steam pipes)

Cardboard

A place with high moisture

A place with direct sunshine

20. HIGH-SPEED TIRE

20-5

HIGH-SPEED TIRE
REMOVAL/INSTALLATION

In comparison with the tube-tire, the
following points must be noticed
when removing and installing a high­speed tire.

•When removing the high-speed tire,

avoid damaging the tire bead (special
plastic seat), tire liner (internal anti­leak material) and rim flange (bead
base).

•Apply vegetable soapy water to the

contact area between the tire bead
and rim, and use a tire iron for
installation.

•It will cause tire deformation when

removing the tire forcedly as the
figure shown. Be sure to remove the
tire following the instructions given
in the manual.

•The tight joint of tire and rim can

prevent air leaks. As long as the rim
is deformed, air leaks will occur
easily. Therefore, do not remove or
install the tire forcedly. Use special
tools and rim protector for servicing.
Frequently check if there is any
deformed part and do not use tools
of poor quality.

•Rust and rubber materials on bead

base are the main cause of air leaks.
Remove them thoroughly.

•Be sure to remove and install the tire

following the procedures provided in
the manual.

• When removing or installing a

high-speed tire, do not damage
the axle bearing. Draw or pull the
rubber on the rim lower part.

• It is difficult to remove a tire

when the rim valve is pressed by
tire flange. In this situation, do
not remove it forcedly because
the rim valve hole will be
damaged.

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