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C
H E C K
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T Y R E S |
Tyre
Structure
• This section will help you identify the main components in a tyre's
structure.
• The inner liner is a special air-tight rubber lining attached to
the inside of the tyre, used instead of a tube.
• The tyre sidewall adds rigity yo to the structure, protecting the
carcass and improving ride quality by allowing the tyre to expand and compress
with the terrain.
• The apex helps to minimise bead distortion and reduce impacts to
it.
• The tread is the part of the tyre in contact with the road. It not
only has to provide grip and cornering stability but must resist abrasion,
cutting, and impacts, as well as withstand high temperatures.
• The bead fixes the tyre to the rim and secures the end of the cord.
It is coposed of a bead wire and rubber core.
• A tyre groove is a channel within the tread that improves driving
stability, pulling ability, and braking ability.
• A tyre belt is made of steel wire or textile fabric. It acts as a
reinforcement, reducing the impacts sustained from the the road and helping
to maintain stability by widening the tread in contact with the road.
• The tyre shoulder is the section from the edge of the tread to the
upper [art of the sidewall. It needs to offer good heat dispersal
• The tyre carcass is the inner cord of the tyre that supports the
weight and absorbs impact. As such it has to resist fatigue caused by the
constant flexing and compression.
• The chafer prevents direct contact between the wheel rim and the
cord to protect the cord.
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Tyre Tread Design
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Groove
A groove is the sunken part of a tyre's tread. Notably grooves are
the fundamental components in deciding a tyre's quality. The groove
improves the braking performance and driving power of a tyre. Groove
depth and design also effects road noise and the rate of a tyre's
treadwear. |
• Sipe
A sipe is a fine groove in the tread pattern. The function of a sipe is
to enhance braking and driving performance, and to provide driving stability
and comfort. In the case of winter tyres it allows grip on icy conditions
through the biting effect of the edge, and also improves braking control
wet roads.
• Rib shape : The pattern along the circumference of the tyre
 |
Good
points : Lower rolling resistance. Good directional stability
and steering control thanks to lateral resistance. Suitable for sustained
high speeds thanks to low heat generation.
Bad points : Poor braking & acceleration grip on wet roads.
Stress caused by flex means tread is more susceptible to cracking.
Use : For paved road surfaces and the steering wheels of trucks
or buses |
• Lug shape : The groove pattern perpendicular to the circumference
of the tyre
 |
Good
points : Excellent braking & driving power. Superior traction
Bad points : Noisy at high speed. It's not suitable for high
speed driving because of high rolling resistance.
Use : For dirt roads, rear wheels of buses, industrial vehicles
and dump trucks. |
• Rib-Lug shape : The combination of Rib-shape & Lug-shape
 |
Features
: The rib in the centre provides directional control whilst the
shoulder lug gives good braking & driving power
Use : Good for both paved and dirt roads. Usually used in both
front & rear wheels of trucks and buses. |
• Block-shape : The pattern of independent block, which the
groove is connected with each other
 |
Good
points : Good steering control and stability on snow covered and
wet roads. Good water dispersal properties on wet roads.
Bad points : Tyre wear is heavy as tread blocks are finer.
Use : Suitable for winter or all-season passenger car tyres.
Suitable for back-wheel of Radial tyre of ordinary car |
• Asymmetric pattern : Tread pattern differs on each side
 |
Good
points : Good for high speed cornering thanks to greater contact
area. Reduces treadwear on outside of tyre.
Bad points : You must position them the right way around.
Use : High performance and motorsport tyres |
• Directional pattern : Lateral grooves on both sides point
the same direction
 |
Good
points : Good driving force and braking performance. Good water
dispersal means good stability on wet roads. Correct choice for fast
driving styles.
Features : mounted in direction of tread pattern
Use : the passenger car tyre for high speed usage. |
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Tyre
Sidewall Markings
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A.
Manufacturer
B. Indication of American certification,
load and speed
C. Product
Name
D. Tube or tubeless
E. Tyre size
F. Indication of structure, load
and air pressure
G. Indication of country of origin |
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Tyre Size markings
P 205/75R 15 84
H
| P |
P
- Identifies a tyre designed primarily intended for service on passenger
vehicles
T- Identifies a tyre intended for one position "temporary use"
as a spare only. |
| 205 |
Nominal
Section Width (mm) |
| / |
|
| 75 |
Nominal
Aspect Ratio |
| R |
Construction
Code: R-Radial D- Diagonal |
| 15 |
Rim
Diameter Code |
| 84 |
Load
Index |
| H |
Symbol
Speed |
31 x 10.50 R 15 LT C 109 Q
| 31 |
Nominal
Overall Diameter (Inches) |
| x |
|
| 10.50 |
Nominal
Section Width (Inches) |
| R |
Construction
Code
"-" - Diagonal, "R" - Radial |
| 15 |
Rim
Diameter Code |
| LT |
Light
Truck Tyre |
| C |
Load
Range |
| 109 |
Load
index |
| Q |
Speed
Symbol |
315
/ 75 R 22.5 154/149 L
| 315 |
Nominal
Section width or Width Code |
| / |
|
| 75 |
Nominal
Aspect ratio (ar=H/S) |
| R |
Construction
Code |
| 22.5 |
Nominal
rim Diameter Code |
| 154/149 |
Load
Indices (Single/Dual) |
| L |
Speed
Symbol |
11.00
R 20 149/146 J
| 11.00 |
Nominal
Section Width or Width Code |
| R |
Construction
Code |
| 20 |
Nomnial
Rim Diameter Code |
| 149/146 |
Load
Indices (Single/Dual) |
| J |
Speed
Symbol |
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Aspect Ratio
| Aspect
Ratio (%) = |
| H |
 |
| W |
|
x 100 |
|
A.
Section Width
B. Rim Diameter
C. Overall diameter
D. Height
E. Product Name
F. Tyre Size
H. Manufacturer name |
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Speed
Ratings
| Tyre
Speed Symbol |
Tyre
Speed Rating |
| km/h |
mph |
| S |
180 |
112 |
| T |
190 |
118 |
| U |
200 |
125 |
| H |
210 |
130 |
| V |
240 |
149 |
| W
(ZR) |
270 |
168 |
| Y
(ZR) |
300 |
186 |
| ZR |
Above
240 |
Above
149 |
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Tyre Choice by Season
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Summer
tyres
The main characteristic of the summer tyre is excellent driving and
braking performance on both dry and wet roads, in temperatures above
freezing throughout the spring, summer, autumn and winter. A simple
block-shape tread pattern ensures the tyre's contact area remains
as rigid as possible, ensuring maximium grip at all times by optimising
friction with the road surface. If the tyre has any special indication
on it, it means this tyre is for summer usage. |
 |
Winter
Tyres
This type of tyre is suitable for snow and ice covered roads. The
tread pattern features a heavily siped, fine-block design with grooves
that are deep and wide, providing excellent driving traction and braking
performance on winter road surfaces. The tread rubber used in winter
tyres provides good friction characteristics and suppleness even in
low temperatures. At present, winter tyre design is focused toward
braking performance and driving control on icy roads. Recent developments
in tyre pattern design and rubber technology have greatly improved
winter tyre performance.. |
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All-season
Tyres
These tyres are designed to be used all year round to save having
to change the tyres to suit the season. All-season tyre patterns are
more complicated than those of the summer tyre because of the longer
block-edge for winter usage. More sipes appear in the all-season tyre
than summer tyre to improve the braking and driving performance by
maximising the effect of edge. It is important to remember that in
regions where winter temperatures are very low and heavy snow falls
are frequent, braking performance will rarely be 100 percent so it
is safer to use winter tyres. All-season tread designs will provide
good all-around traction for varing road conditions, but still provide
good treadwear and tyre noise characteristics.
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Tyre
Maintenance
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Tyre
Rotation
Tyre wear differs depending on the position where the tyre is located,
so to extend the life of your tyres it is important that you change
their positions on a regular basis. Different tyre manufacturers may
recommend different rotation periods, though as a general rule you
should rotate them every 2000 - 3000 miles (approximately 3,000 -
5,000 km.) |
 |
Tread
Wear Indicator
A tyre is a wearing part that will need replacement after a period
of time. When the groove depth reaches 1.6mm you are required by law
to replace the tyres. It is advisable to replace them before they
have reached this limit, to benefit from deeper tread in adverse conditions.
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Tyre
Catagory
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Radial tyres are designed so that cord of the carcass is perpendicular
to the centre line, and a strong belt is attached it above for added
stability even at high speed. |
Bias
tyres feature a carcass where the angle of the cord to the centre
line is 35 degrees. |
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Tyre
Safety
• You
must not use a tyre which has a tread under 1.6 mm
Tyres with tread under this limit will slide easily, suffer from extended
braking distances and will be more susceptible to rupturing. In wet conditions
the vehicle will aquaplane, making braking and handling almost impossible.
Tyres with tread under this limit are illegal and may lead to a fine or
disqualification.
• Incorrect air pressure shortens the life of the tyre
If you drive with low air pressure in your tyre, heat is generated in the
tyre. This can result in the rubber and cord separating, which in turn leads
to the cord becoming cut and puncturing the tyre. Low pressure can wear
the edge of tyre which will shorten the tyre's life.
Excessive pressure results in the tyre becoming unpredictable. If the tyre
suffers an impact, it is easily ruptured and cut. If you brake hard, the
tyre may skid, which reduces tyre life as the centre of the tread becomes
worn.
• A damaged tyre can rupture during operation
If you drive with materials such as stone in the tread groove, or with a
nail stuck in the tyre, the tyre can become punctured or ruptured. You should
change the tyre immediately on discovering any damage to avoid any further
damage to the carcass.
• Abnormal tyre wear should be treated instantly
In absence of good maintenance, abnormal wear may occur due to sudden braking.
You should check air pressures, alignment and rotate the tyres regularly.
In addition you should avoid bad driving habits such as sudden acceleration,
braking and cornering.
• Check the spare tyre
Make sure you regularly check the spare tyre's air pressure, existence/non
existence of damage and the depth of remaining grooves regularly.
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