The simensions of a motorcycle tire are indicated here.In [612327]

The simensions of a motorcycle tire are indicated here.In
contrast to other types of tires,the tread width of motorcycle
tires is normally wider than the section width.The section
width included in the size marking of tires.A tire marked"120/90-18" means that the section width of the tire is 120
mm.
Most motorcycle rims used tod are MT type drop center
rims.We call this a "hmp-up" type of rim.this type of rim is
used for tubeless tires because it helps keep the beadportion of the tire in place even if the tire is punctured.About
ten years ago we did not have this type of rim because most
of the motorcycle tires still tube type.
Other important dimensions include the overall
diameter,section height,crown radius rim diameter.
The "Aspect Ratio"is defined as the ratio of the section
height divided by the section width multiplied by onehundred.
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4ɾThey must Changing & maintaining the direction of travel.Motorcycle tires must perform main functions:
3ɾThey must absoring shocks from the road surface.1ɾThey must support vehicle load.
2ɾThey must transmit traction and braking forces to the road surface.#BTJD
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*Inch designations
4.00 H 18 4PR
Casing strength (ply rating)
Rim diameter
Speed rating
Tire width (inches)
*
Racing tire designations (for Bridgestone)
180 / 630 – 17
Rim diameter (inches)
Overall diameter
Tire width (mm)*
Metric designations
130 / 80 – 18 66 H
Load rating
Rim diameter (inches)
Aspect ratio ( 80%)Speed rating
Tire width (mm)
*
Alhabetical designations
M T 90 – 16 LOAD RANGE B
Rim diameter (inches)
Aspect ratio ( 90%)
Tire width codeLoad rating
Motorcycle code

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TypeMaximum speed( km/h )
Motorcycle useOn-road N type
On-road S type
On-road H typeOn-road V type180
210>210**
100
80
150**
Scooter use
Flotation type(low I.P)112
130>130**
62
5093
km/h (mph )
Numbers in box:00,25,50,75
100=aspect ratio90=aspect ratioNumbers in box:1,670=aspect ratio
140/ 70 -184. 6 OH18120/ 90 -1880/ 100 -182. 00 -14
70Series 80Series 90Series100SeriesStandard( 94ʙ100)Aspect ratio Size Indentification "DDPSEJOH
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**On-road V type tires are made for export..PUPSDZDMF
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Tread
The construction of motorcycle tires is basically the
same that of passenger and light truck tires. The
unique difference, however, is its shape-the crown areaof a motorcycle tire is quite rounded.
The casing of the tire in this illustration begins on the
inside and is turned up around the beads. Two actual
casing plies are shown here which would normally
correspond to a four ply rating. On the top of the casingand underneath the tread area of the tire, the breakers
or belts are applied. Breakers are usd for bias ply
construction tires and belts for radial construction tires.The term "breaker" evolved from the fact these layers
of reinforcing material were meant to break the impactof shocks in the tread area of the tire, protecting the
casing. Breakers are normally made of nylon while
belts for radial tries are usually steel or aramid cord.
In the enlarged drawing of the tire's "bead area", you
can see the bead wire the bead filter. The bead filterincreases tire stiffness in the bead area. If, for
example, the stiffness of this area is insufficient, the
motorcycle will not be stable when cornering and tirevibration might occur. A hard rubber compound is used
for the bead filter. A protecting ply called a "chafer" is
wrapped around the bead area the bead area toprotect it from being damaged by rubbing (or "chafing")
on the rim.Enlarged view of bead areaCasingBreaker (cap belt)
Inner liner
Bead filler
Bead
Rim lineSidewall
Bead fillerFlipper
Bead heel
Bead baseBead toeBead wire
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0˃ 10˃ 20˃ 30˃ 40˃A Large Camber Angle Is Used When Turning
Use rangeMotorcycle tire
Passenger car tire
(Bias)
Passenger car tire
(Radial)4QFDJBM
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Another special characteristic of motorcycle tires is the
use of large camber angles when tuning. Forpassenger tires, the maximum camber angle is
normally 5, but for motorcycles, it can be as 50 in
corners. Although it c not occur under normal operatingconditions, when a passenger car tire has a camberangle of around 30 or more, it is running on the
sidewall. Motorcycle tires, however, are designed sothat the contact area will not chance when high camber
angles are used. This is done by extending the tread
surface from sidewall to sidewall.
Motorcycle tires have acrown contour and basic construction
which produces a minimal change in contact area when turnig.4QFDJBM
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Motorcycle tires exhibit several characteristics
according to their application. One of these features
can be seen in this graph. The vertical axis shows the
ratio of contact pressure to inflation pressure while thehorizontal axis shows the load per drive tire. Note that
the drive tires of trucks support about 2000 kilograms
per tire and that the contact pressure to inflationpressure ratio is about 0.8 Motorcycle tires, however,
are on the other end of the scale. The load per tire is
around 250 kilograms but the ratio of the contact
pressure to the inflation pressure can exceed 1.4-almost twice the value for truck tires. This means that
the load per square centimeter for motorcycle tires is
very concentrated.


    
Load per drive tire LH
Motorcycles
Passenger car
Light & medium
sized trucks
Large trucks


Contact pressure / Inflation pressure




    
Load per drive tire LH
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Passenger car
Light & medium
sized trucks
Large trucksHorsepower/cmThe ratio off the contact pressure to the
inflation pressure is relatively high for
the tire load.
Motorcycle tires are used under very
different conditions than other types of
tires.
Horsepower per unit of contact area is
very high (2X's the maximum level for
passener cars and about 5X's that for
trucks).
Motorcycle tires are used under very
different conditions than other types of
tires.Load on drive tires vs.ratio of contact pressure to inflation pressure
Horsepower per unit of contact pressure
We can also see that the horsepower per unit of
contact area is very high as compared to other types oftires-nearly twice as high as the maximum value for
passenger cars and five times that for trucks. The large
variation in the amounts is due to the many differentsizes of motorcycles. Larger motorcycles would be on
the upper end of the scale. The horsepower acting onone unit area of tread for motorcycles is much higher
than that for trucks.

Crown Buttress SidewallBending stiffnessPassenger car tire (Radial)
Motrocycle tire
Passenger car tire (Bisa)High and Uniformly Distributed Casing Stiffness
If radial motorcycle tires were constructed the same
way radial passenger car tires are, the sidewalls wouldbe too soft. This would mean that the tire would not be
able to produce the necessary amount of camber
thrust. To counteract this, we apply an extra-hard beadfiller, one or two "cap-layers" which extend down thesidewall, and several other components such as
special chafers and/or flippers to increase the stiffnessof the sidewall. These additional materials increase the
overall cost of the tire to about two times that of a bias
motorcycle tire of the same size. This is one of thebiggest problems confronting us.



   Motorcycle tires
Passenger car tires (Radial)Passenger car tires (Bisa)
Camber angleCamber thrust (kg)The Effect of Camber Thrust Is Large
When a motorcycle is cornering, the camber thrust
produced by the tire in response to the camber angle isquite high and offsets the centrifugal force. For
passenger car tires, however, the camber thrust is
much lower. Aradial passenger car tire will produceonly about 50 kilograms of camber thrust at a camberangle of 20. A motorcycle tire will produce around two
times that amount at the same angle. For this reason,the sidewall area of motorcycle tires must be very stiff
to endure this amount of camber thrust. This is one
reason why we use the cap layer construction.
Camber thrustCamber angle
TireSlip angle Cornering
force
Direction of
vehicle travelTire type vs.camber thrust
The graph on page 5-006 is included to illustrate the fact that
not all of the cornering force for motorcycles can be classifiedas camber thrust. Additional cornering force due to a slip angle
is also present-much like the case for passenger cars. This type
of cornering force therefore makes up the rest of the overallcornering force. This is often called "tail work – ing".
В:Camber angle(angle of bank)
W:Overall weight(rider plus vehicle)
V :Speed
r :Cornering radius
g :Acceleration of gravity

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1.Shimmy
Left and right vibration of the steering assembly while
driving in a straight line.
Low speed shimmy
Occurs when coasting down from around 80km/h,
peaks at around 45-50km/h. (vibration frequency: 3-
5Hz)
High-speed shimmy
Occurs at around 110-120km/h, the magnitude is small(vibration frequency: 10-15Hz)
Cause
A phase difference between the corning force and theself aligning toque.
Tire related factors
Wear stage, inflation pressure (high inflation pressureis better as it reduces the contact area), tread gauge,
tread compound characteristics, casing stiffness, cord
angle, etc.
2.Wobble
Left and right vibration of the motorcycle frame at highspeeds. Occurs both on straight-aways and in cornersand arises mainly from the rear wheel. (Vibration
frequency: 2-3Hz)
Cause
Resonant vibration of the front and rear of the
motorcycle caused by side forces arising from outsidedisturbances. In corners it is due to the imbalance ofside forces from camber thrust, oversteer moment,
cornering force and centrifugal force.
Tire related factors
Wear stage, inflation pressure, tread gauge, tread
compound characteristics, casing stiffness, cord angle,
balance of front and rear sizes.
3.Rain Grooves
Rain grooves are grooves cut in the road surface forsafer driving on wet surfaces. Some types are parallel
to the vehicle direction of travel and others are
perpendicular to it. In the U.S. the U.S. these aremainly found in California but their use is spreading to
other states as well.
Left and right vibrations are caused which aretransmitted to the motorcycle frame and steeringassembly, leading to instability.
Cause
Tire tread pattern edges on the groove edges, forcingthe tire to one side or the other.
Tire related factors
The contact of a number of tread pattern edges with
the rain grooves at the same time must be prevented
therefore "zig-zag"type patterns are usedalong with designs
that equally distribute
the contact pressure.(MPTTBSZ
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The technical terms found here areuseful for standardizing thenomenclature used to describevarious aspects of motorcycle
performance factors.
1. Shimmy is usually related to
steering and is sometimes called
"Steering shimmy". It is defined as"left and right vibration of thesteering of the assembly while
driving in a straightline". Shimmy is
direly related it the match of themotorcycle and tires. An exampleof a difficult matching problem can
be seen in the newly developed
Suzuki GSXR750. The frame ofthis motorcycle is very light for its
engine size and therefore thehorsepower to weight ratio is quite
high. Usually the weight of a 750 ccmotorcycle would be around 220-240 kilograms but the weight of the
Suzuki GSXR750 is less than 200
kilograms. This makes matching atire to the machine very difficult.
2."Wobble" affects both the
steering alone and the motorcycleframe. Wobbling is normally
caused by ununiformity of the tires.
For example, each tire may not beperfectly round or the rim may bebent. As a result, vibration of the
motorcycle may occur. Various tire
related factors are also listed.Casing stiffness means that the
stiffness of the casing around thecircumference of the tire is nor
even.
3."Rain grooves" are grooves cut in
the road surface which channel
away rain water, preventing tirefrom hydroplaning. If the tread
pattern happens to be designed so
that two or more of the grooves inthe line up with two or more thegrooves in the road, forces are
generated which make the tire pull
to one side. This can causedirectional instability. Bridgestonealways considers this when
designing tires for the U.S.A. Often
a zig-zag type pattern isimplimented to overcome the
problem.
Left and right vibration of the steering assembly
Low speed shimmy:
Occurs when coasting down from around 80km/h and peaks at around 45-50km/h. It can
1Shimmy have various magnitudes and its frequency is about 6-5 Hz.
High speed shimmy:
Occurs at about 110-120km/h.Its magnitude is small and it has a frequency of about 10-
15Hz.
1Wobble (wobbling)Left and right vibrations of the frame at high speeds (a yawing movement). It mainly arises
from the rear and has a frequency of about 2 to 3 Hz.
1Tail WorkingMovement of the rear of the motorcycle during cornering-not skidding. The frequency
range is around 1-3 Hz.
1Pitching/JudderVertical vibrations in the same direction as the or travel. Similar to the phenomenon
experienced when using tires with poor uniformity.
1SloppinessA type of movement occurring during cornering and arising from the rear wheel. Although
the tire follows the normal oath, the rim and suspension move in a slightly different path.
1Slippery FeelingA feeling that the motorcycle is just about break away. It is caused by growth of the tire
overall diameter or load shifting toward the rear wheel.Term PhenomenonWobbling and weaving are quite similar. Note that they
both have frequencies in the same range (1-3 Hz).
Pitching occurs more frequently than wobbling or
weaving. It is similar to the pitching of a ship and notvery comfortable for the rider.The term "slippery feeling" is rather difficult to describe
but notice that not refer to the movement of the tire with
respect to the road but rather to a shift due to
deflection of the tire itself. It is similar to yawing insome ways.4QFDJBM
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The contact width is shown here. If a tire is not
designed well, its contact width will suddenly change
when the bike leans over-in other words, when acamber angle is applied. When this happens during
cornering, the grip is decreased and the bike becomes
very hard to control. To solve this problem, we designthe tires so they can maintain a constant contact width.Ten years ago the footrests of motorcycles would touch
the ground at a camber angle of 35 to 40 degrees.
Nowadays, however, riders can lean their bikes up to50degrees-which often happens during circuit-type
racing. We make tires so the contact patch will become
large when bike is learning, increasing safety andstability.4IBQF
Contact width
A
BLarge contact area
Actual contact area
110/80-18 Smooth transition of contact
width with in camber angleContact width
Gradual increase in contact area
Camber angleMotorcycle riders demand better handling and better
mileage. To design tires, however, we need more
detailed classifications of performance.
Straightaway stability, cornering stability and low-speedturning all refer to handling performance. Overall
performance is actually a combination of these. What
we to know are the smaller classifications. If ridersmention handing, we must know what aspect of
handling they are referring to.
Straightaway stability. When traveling in a straight line,
the motorcycle will be stable even if the wind isblowing, etc. This term refers to outside influences.
Some tires have poor stability when changing lanes to
pass a car, etc. This could be the result of two
influences. Stability with regard to outside influencesand stability of the tire itself (e.g. when changing
lanes).
Cornering stability. Taking a corner at high speeds can
result in poor cornering stability. Steering must then be
corrected. When a tire has good cornering stability, we
can keep a constant steering angle..PUPSDZDMF
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1Straightaway stabilityReduction of the influence of shock, etc. arising from outside influences
(such as the road surface, wind, etc.) for smooth & stable straightaway
performance
1Cornering stability Minimization of outside disturbances for stable and precise cornering
1Low-speed turning Ease and stability of turning at very low speeds
1GripBalancing of front and rear grip at a high level during braking and
cornering
1Rain groove performance Stable travel over rain grooves
1Wear life Resistance of tread rubber to wear.
1High-speed durability Sufficient durability at high speeds
1Air holding & run flat performance Resistance to air leakage during use, rim retention after sudden air loss
1Pattern noise Low noise generation level

Grip is often referred to generally but if it is analyzed in
detail, we find that there are two main kinds. One kindis the grip caused by friction-this refers to bonding or
"sticking" that takes place between rubber molecules
and the molecules and the road surface. This is due toadhesion.
Another kind of grip is caused by hysteresis loss which
occurs when the tire deforms because of uneven read
surfaces. This rubber deformation causes a loss of
energy in the tires. For example, if 100% of the enginepower is actually transmitted to the road surface, then
there would be no loss of energy. If, however, due to
deformation, five to ten percent of the power is lostbefore it reaches the road surface, this is called a
hysteresis loss and results in generation of grip.
As can be seen in this graph, when motorcycle speedis low, the force of adhesion is quite large, but at higher
speeds, the force generated by hysteresis loss
becomes the main factor. For high performance tires,
the grip factor related to hysteresis has to be quitelarge to produce better grip at higher speeds. This is
accomplished through compounding. If we use NR, for
example, grip will be high because of the rubber'ssoftness but the tire's wear resistance will be quite low.
To overcome this dilemma, we mix in synthetic rubber.
There are types of synthetic rubber with highhysteresis loss but since they are very expensive, wecan them together with other polymers. At this time we
are applying a racing-type compound to the Spitfire
tire..BUFSJBMT
The rigidity (bending stiffness) of normal tires is the
same from the tread all way to the sidewall (i.e. the
stiffness of the tread and buttress areas). For highperformance motorcycle tires, however, engineers
increase the stiffness of the shoulder and sidewall
areas for better cornering and stability.$POTUSVDUJPO
Proper matching with
the motorcycleShoulder Sidewall BeadOptimization of
rigidity from tread
area to bead areaProper stiffness distribution
Soft, high loss tread compound
Friction Forces (Pneumatic Tire Friction by D.F. More)
F=FHYST +FADH
Friction force=Force due to hysterisis loss
V+Force due to adhesion
Matching of compounds to
performance requirements

Design
conceptPerformance +AppearanceDifferentiation
according totireapplications1BUUFSO
Usually when we design a new pattern, we don't start
with the pattern itself but rather with the basic productconcept that we are pursuing. For example, if we are
aiming at a tire for a sports or a touring bike, we would
come up with an image of what the tire tread wouldlook like. At this point, since we are still dealing with animage, we must consider whether the performance of
the pattern will be good or not. For example, if we
design the pattern in the center of the tire, the wet
performance may not be accpetable because thegrooves are very narrow. We would therefore modify
the tread design.
Pattern design method
Battlax/Spitfire(SE-02)
Example
Desired Image
Dynamic
FastImpressive}Lightning