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Check Tyre Pressures

Tyre Anantomy, Design and Construction

Tyre Structure

Tyre Anantomy, Design and Construction
• 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

Tyre GoovesGroove

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.

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
Tyre Rib ShapeGood 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
Tyre Lug ShapeGood 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
Tyre Rib-Lug ShapeFeatures : 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
Tyre Block ShapeGood 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
Tyre Asymmetrical PatternsGood 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
Tyre Direction patternGood 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

Tyre Sidewall MarkingsA. Manufacturer

B. Indication of American certification, load and speed

Product Name

Tube or tubeless

Tyre size

Indication of structure, load and air pressure

Indication of country of origin
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Tyre Size markings

P 205/75R 15 84 H
PP - 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.
205Nominal Section Width (mm)
75Nominal Aspect Ratio
RConstruction Code: R-Radial D- Diagonal
15Rim Diameter Code
84Load Index
HSymbol Speed
31 x 10.50 R 15 LT C 109 Q
31Nominal Overall Diameter (Inches)
10.50Nominal Section Width (Inches)
R Construction Code
"-" - Diagonal, "R" - Radial
15 Rim Diameter Code
LTLight Truck Tyre
CLoad Range
109Load index
QSpeed Symbol
315 / 75 R 22.5 154/149 L
315Nominal Section width or Width Code
75Nominal Aspect ratio (ar=H/S)
RConstruction Code
22.5Nominal rim Diameter Code
154/149Load Indices (Single/Dual)
LSpeed Symbol
11.00 R 20 149/146 J
11.00Nominal Section Width or Width Code
RConstruction Code
20Nomnial Rim Diameter Code
149/146Load Indices (Single/Dual)
JSpeed Symbol
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Aspect Ratio
Tyre Aspect Ratio
Aspect Ratio (%) =
 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 SymbolTyre Speed Rating
W (ZR)270168
Y (ZR)300186
ZRAbove 240Above 149

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Tyre Choice by Season

Summer TyresSummer 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 TyresWinter 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..

All Season tyresAll-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

Tyre RotatioinTyre 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

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 category

Tyre category
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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Replacement Tyre Selection

How Cold Temperature Affects Tyres

The Legal requirements for legal tyres on UK cars

Tyre-Related Factors in the Pre-Crash Phase

Vehicle Conditions Affecting Tyres

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