Tyres and wheels have several important functions for vehicles. Tyres provide cushioning from rough roads, allow steering and braking, and provide traction through friction with the road surface. Wheels support the vehicle's weight and allow it to move. There are different types of tyre construction like bias ply, belted bias, and radial ply. Radial ply tyres offer advantages like reduced rolling resistance and better handling. Wheels are typically made of steel or aluminum and properly torqued fasteners are needed to securely attach the wheel to the vehicle.

1. Tyres & Wheels

2. Introduction
Functions
• Supports the load on vehicles
• Act as the primary suspension, cushioning the vehicle from
effects of rough surface.
• Allows the wheels to steer
• Helps to get best acceleration
• Provide frictional contact with the road surface which allows
the driving wheels to move the vehicle
• Tyres allow braking to slow or stop the vehicle

3. Properties of tyres
• Non-skidding: – The tyre should have good grip so that it can overcome
skidding.
• Noise resistant: – There should be minimum noise from tyre during driving.
• Optimum Load carrying capacity: – The tyre size and material should be
selected in such a way that it can carry vehicle load and withstand with
fluctuating stress during revolution.
• Minimum power consumption: – Tyre transmits power from engine to road
so there should be minimum power loss in tyre to get better efficiency.
• Uniform wear: – The wear around the tyre should be uniform so that there
is no issue of unbalancing.
• Should be well balanced: – The weight and dimensions of all tyre are such
that, that it is dynamically balanced.
• Satisfactory cushioning: – The tyre should have good shock absorbing
property so that it can absorb vibrations by road to provide cushioning
effect.

4. Terminology
• Steel Wheels – Most popular design. Very strong and cheap to produce.
• Alloy Wheels – Attractive and light weight, but expensive and difficult to clean.
• Spoked Wheels – Used on older vehicles. Cannot be fitted with tubeless tyres.
• Divided rims – Rims are made in two halves which are bolted together, (rims
must never be separated while the tyre is inflated)
• Split rims –Tyre is held in place by a large circlip
• Plies – Layers of strong fabric which are built up to give the tyre its strength
and shape
• Bead – loops of steel which are the anchor point for the plies
• Cross Ply Tyre – Main plies of the tyre run at an angle (45 degrees) from one
bead to the other
• Radial Ply Tyre – Main plies of the tyre run at 90 degrees from one bead to the
other
• Tread – Rubber pattern. Provides grip with the road surface and assists in
clearing water away
• Side Wall – Connects the beads to the tread of the tyre

5. Parts

6. 1. Belts: These are rubber-coated layers of rayon, Steel fiberglass and other
materials which are located in mid of the tread and plies, across at angles,
which hold the plies in place. It provides resistance to punctures and help
treads to in contact with the road.
2. Sipes: These are special kind treads within the tread which improves tractive
effort on different road surfaces.
3. Tread: It is the portion of the tire that comes in directly contact with the
road. It should have higher strength and good heat dissipation property for
good life of tyre.
4. Grooves: It is the spaces provided on the outer layer of tyre which comes in
contact with road. It provides space for water to flow and friction.
5. Shoulder: It is the outer edge of the tread which wraps into the sidewall
area.
6. Sidewall: It is the portion of tyre which is exposed to environment and not
come in contact with road . It protects cord plies. it is also used to feature tyre
markings and information such as tyre size and type.
7. Inner Liner: It is the innermost layer of a tubeless tyre. It prevents the flow of
air from inside to outside and vice versa.
Parts

7. Carbon black adds strength and abrasion resistance,
while protecting rubber against UV light.
During curing, sulphur links rubber molecules
together, adding strength, and giving the rubber
resistance to both heat and cold.
Zinc stearate
Small amounts of zinc stearate and waxes help control
curing rate, prevent oxidation and make rubber easier
to process.
Accelerators are used to control the cure rate, so
different types of rubber can cure fully – in same
amount of time.
Antioxidants and antiozonants are added to rubber to
fight degradation by oxygen and ozone, which can
shorten the life of tyres.
C
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8. Tyre Cutaway

9. Bias Ply Tyre Construction
• One of the oldest design
• Several textile plies are laid across
each other, running from bead to
bead in alternate directions
• Number of plies depends on the size
of the tyre and the load it has to
carry
• Same number of plies is used on the
crown and the sidewalls
• Plies run at an angle from bead to
bead
• Does not use belts
• Allows body of the tyre to flex easily
• Improved cushioning, hence smooth
ride on rough roads
• Weakness: Reduced traction at high
speeds and increase rolling
resistance

10. Belted Bias Tyre Construction
• Bias ply tyres with belts added to increase tread stiffness.
• Belts do not run around the sidewalls, they lay under the tread area
only
• Belts and plies run at different angles
• Offers some reduction in rolling resistance over a bias ply tire
• Provides smooth ride and good traction

11. Radial Ply Tyre Construction
• Plies run straight across from bead to
bead.
• Has a very flexible sidewall and a stiff
tread, giving it a very stable footprint
• Consist of a carcass ply formed by
textile arcs running from one bead to
the other.
• Each ply is laid at an angle of 90
degrees to the direction the tyre rolling
• At the top of the tyre crown (under the
tread), a belt made up of several plies
reinforced with metal wire is laid.
• These crown plies, laid one on top of
the other, overlap at an angle
determined by the type of the tyre.

12. Advantages of Radial Ply Tyres
• Side walls can bend easily, its shock absorbing capacity is 25% more than
bias ply or cross ply.
• Lower rolling resistance and hysteresis loss leads to less fuel
consumption
• Longer tread life because of less heat build in tyre.
• Breaking efficiency on wet roads is better because of greater sidewall
flexibility and tread stiffness.
• Better steering characteristics.
• While taking turns it has less tendency to distort and lift off the road
from one side.
• Larger resistance to punctures ,cuts and impacts in the tread area.

13. Non-Directional Tyres
Uniform grooves
Can run in any direction
Unidirectional Tyres
Grooves are in one direction
Direction of rotation is clearly marked

14. Cross-section of tubeless tyre

15. Advantages of tubeless tyres
• Lesser unsprung weight.
• Better cooling
• Lesser rolling resistance
• Comfortable ride
• Slower leakage of air
• Simpler assembly
• Improved safety

16. Tyre Sidewall Markings

18. Speed Rating

19. Load Rating
Load
Index
Load
(Kilograms)
Load
Index
Load
(Kilograms)
71 345 91 615
72 355 92 630
73 365 93 650
74 375 94 670
75 387 95 690
76 400 96 710
77 412 97 730
78 425 98 750
79 437 99 775
80 450 100 800
81 462 101 825
82 475 102 850
83 487 103 875

20. Tread Patterns
Competition
Snow tyres

21. Feathering
• Improper alignment (TOE).
•Worn or damaged steering/ suspension
parts.
• Hard cornering
Cupping
•Worn or damaged steering or
suspension parts.
•Improper balancing.
One Edge
•Improper alignment (CAMBER).
•Worn or damaged steering or
suspension parts
Tyre problems

22. Mechanical Irregularities

23. Mechanical Irregularities

24. Camber
Right side tyre

25. Tread Wear Markings
Tread wear indicator
Wear Measuring tool Coin method

26. Nitrogen in Tyres
• Makes up around 80 percent of the air
• Dry inert gas. It is less reactive than oxygen.
• Leaks out of the sidewall three times slower then oxygen.
• Oxygen oxidizes the rubber in the sidewall.
• Pumped into tyres in a pure form, hence it does not contain
moisture found in compressed ambient air which causes
rusting of steel rims.
• The result is that all materials that come into contact with the
compressed gas inside the tyre are less subject to oxidation
corrosion

27. WHEELS
• Wheels along with the tyre has to take the vehicle load, provide a
cushioning effect and cope with the steering control.
• Various requirement of an automobile requirement are:
1. Strong enough to perform the above functions.
2. Balanced both statically and dynamically.
3. Possible to remove or stand the vehicle wheel easily.
4. As lightest as possible so that the un-sprung weight is least.
5. Easy to clean, easy to wash and be of good quality.
6. Should not deteriorate with age and weathering. If material is vulnerable
to corrosion, must be given suitable protective treatment.
7. must be of maximum strength to take the weight road shocks, driving
torque and must be able to compensate all sorts of load varying in
magnitude and direction.
8. must be strong enough to resist local deformation or when it hits a road
kerb or any other obstacle.

28. Wheel - Basics
Pilot bore fits to the hub.
• Most standard wheels are made of
steel.
• Some vehicles are fitted with alloy
wheels that are made of magnesium
or aluminum
• The rim holds the tyre.
• Well of the wheel allows the tyre to
be removed and refitted
• Centre section is welded to the rim
Centre mounting section
Rim

29. Wheel - Basics

30. Valve Stems and Cores
Functions – Retains air, allows inflation and deflation.
Rubber stem of the valve is pulled
into the wheel.
Valve core contains a spring loaded air
valve insert.
The valve core also has a sealing
washer and a seat washer.
Valve cap keeps out dust
and helps keep air in.
Valve caps
Sealing
washer
Seat
washer
Valve stem
Valve core
Tyre pressures must only be checked
and adjusted when the tyre is cold

31. Taper on the wheel nuts secures
and centers the wheel.
Wheel studs usually have a right-hand
thread.
If it is a left-hand thread, it can be
marked with “L”.
Metric threads are marked with “M” or
METRIC.
Wheel studs press through the
hub or axle flange.
Wheel Fixings
Wheel studs and nuts attach the
wheel to the hub.
Taper
Wheel mounting
Hub flange

32. Torque
wrench
Wheel Nut Torque
Correct torque of wheel fixing is vital for
all vehicles, and nearly all require the
use of a torque wrench.
Excessive torque can lead to wheel or
hub distortion, causing runout and
vibration.
Low torque may allow wheel nuts to
work loose and wheels to come off.
Nuts should always be tightened in a
diagonal pattern.

33. Types of Wheel

34. • Direction or speed change relies on friction between the tyres and the
road surface.
• Grooves of a rubber tyre are designed to disperse water from under the
tyre, providing high friction even in wet conditions.
• Aquaplaning occurs when a tyre encounters more water than it can
dissipate
• Steering appears light as if we are driving with wheels in air
• Water pressure in front of the wheel makes a wedge of water under the
leading edge of the tyre, causing it to lift from the road.
• This loss of traction causes the wheels to slip and prevents the vehicle
from responding to steering, braking or accelerating. As a result, the
vehicle can go out of control, start to skid or spin.
• Risk of aquaplaning increases with the depth of standing water
• If multiple tyres aquaplane, the vehicle loses directional control and slide
until it either collides with an obstacle, or slows down so that friction is
regained.
Aquaplaning (Hydroplaning)

35. • Tyre tread wear: Worn tyres will aquaplane more easily due to lack of
tread depth.
• Tyre inflation pressure: Under inflation enhances aquaplaning
• Tyre tread aspect ratio: Longer and thinner the contact patch, less likely
a tyre is of aquaplaning. (Small diameter and wide tyres are more
prone to aquaplaning)
• Vehicle weight: More weight on a properly inflated tyre increases the
contact patch. Weight can have the opposite effect if the tyre is
underinflated.
• Vehicle type: Combination vehicles like semi-trailers are more likely to
experience uneven aquaplaning caused by uneven weight distribution
SOLUTION:
If aquaplaning is encountered (steering feels disconnected), DO NOT
brake, accelerate, or steer the vehicle. Allow the speed to reduce on its
own
Aquaplaning (Hydroplaning)

36. Aquaplaning (Hydroplaning)