good

1. OFF ROAD TIRES
INSTR.Engr.Farid ullah

2. Tires
• Tires are considered as the most important part of your automobile
because they affect almost every performance factor like braking,
acceleration, handling and comfort.
• It provides good grip to the surface to avoid slipping and skidding
condition so that it can work well on dry and wet road.
• Functions of Tires
• It supports the load on vehicles
• It absorbs shock during motion
• It enables to take turn to left or right
• It helps to get best acceleration and braking

3. Properties of Tyres
• . Non-skidding: – The tyre should have good grip so that it can overcome
skidding.
• 2. Noise resistant: – There should be minimum noise from tyre during driving.
• 3. 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.
• 4.Minimum power consumption: – Tyre transmits power from engine to road so
there should be minimum power loss in tyre to get better efficiency.
• 5. Uniform wear: – The wear around the tyre should be uniform so that there is
no issue of unbalancing.
• 6. Should be well balanced: – The weight and dimensions of all tyre are such
that, that it is dynamically balanced.

4. Main Components of Tyres
1. Tread. Made from synthetic and natural rubber, it’s comprised of three sections: the
“cap”, which is responsible for gripping the road and providing directional stability and
wear-and-tear resistance, the “base” which reduces rolling resistance and damage to
the casing and the “shoulder” which forms an optimal transition from the tread to the
sidewall.
2. Jointless cap plies. Found just underneath the outer layer of the tyre, this nylon
cord, embedded in rubber, enhances high-speed suitability.
3. Steel-cord for belt plies. High-strength steel cords that enhance shape retention
and directional stability. As well as reducing the rolling resistance they help to increase
the tyre’s mileage performance.

5. Main Components of Tyres
• 4. Textile cord ply. Rayon or rubberized polyester controls the internal pressure and maintain’s
the tyre’s shape.
• 5. The inner liner, made from butyl rubber, seals the air-filled inner chamber and acts as a tube in
tubeless tyres.
• 6. The side wall protects the casing from external damage and atmospheric conditions.
Information about the tyre can also be found on the side wall.
• 7. Bead reinforcement, made from nylon and aramid fibres, enhance directional stability and
ensure steering precision.
• 8. Bead apex. This synthetic, rubber material also enhances directional stability and steering
precision while improving comfort.
• 9. Bead core. This steel wire, embedded in rubber, ensures that the tyre sits firmly on its rim.

7. Types of tyres

8. • A) On the Basis of Tube used:
• 1. Tube Tyre: It is the most commonly used kind of tyre. It encloses a
rubber tube which is filled with air at high pressure. The outer part is made
of synthetic rubber which is known as tread. Inside tyre beads are formed
with the help of reinforced steel wires. Beads works as strong support for
wheel rim. A number of piles are formed by rayon cords. Cords provide
strength to the tyres.
• 2. Tubeless Tyre: In current time use of this tyre are continuously
increasing. This tyre does not enclose tube. The high pressure air is filled in
tyre itself. The internal features and construction of this tyre are same as
tube tyre. An NRV (non-return valve) is fitted to the rim for air filling.
• Advantages of Tubeless Tyre
• They enhance the ride quality and make it comfortable.
• These tyres permit slower leakage of air.
• These tyres have less weight.

9. • B.On the Basis of Construction:
• 1. Cross Ply Tyre Construction: It is also known as bias ply tyre construction. This
tyre has better a resistance against wear. They have good bonding to the road.
Cross ply tyres consist of carcass (casing) layers made from nylon cord which are
placed diagonally along each other in the tread and the sidewalls, at an angle of
50 degrees.
• Multiple rubber plies stacked over each other which form a thick layer, which
makes them less flexible as a result they are more sensitive to overheating. These
tyres give a strong and rigid sidewall.
• Advantages of Cross Ply Tyre
• These tyres provide high vehicle stability.
• They also provide good resistance against sidewall damages.
• These tyres are economical as their production is cheaper.
• Disadvantages of Cross Ply Tyre
• Due to the rolling resistance these tires heat up quickly.
• Cross ply tires being rigid, prove to be less comfortable.
• Due to high resistance of the tire, the fuel consumption is high

10. • 2.Radial Ply Tyre Construction:It consists of a carcass ply which is
formed by textile arcs running one bead to the other. Each ply
embedded at an angle of 90 degree to the rolling direction. At the top
of tyre crown several plies is reinforced with metal wire on the top of
carcass ply.

11. • Advantages of Radial Ply Tire
• • These tyres have a lower rolling resistance loss which leads to less
fuel consumption.
• They have a longer tread life as less heat generated.
• They provide better braking efficiency.
• They have larger resistance to punctures and cuts.
• Disadvantages of Radial Ply Tire
• These tyres have a steel belt due to which it does not fare well against
minor bumps in the road.
• Their soft sidewalls are weak.
• Due to harder tread they make huge noise.
•

13. Bias tire construction
• A bias tire consists of multiple rubber plies over lapping each other at
a 30-45 degree angle. The tread and sidewalls are interdependent
because all plys have a consistent angle. The overlapped plies form a
thick layer that is less flexible which makes it able to carry a heavier
load and less trailer sway. You will typically have a smoother ride,
lower noise, better handling

14. Tonne Kilometres Per Hour(TKPH)
• TKPH stands for Tonne Kilometres Per Hour. TKPH is a method of
answering one of the fundamental questions regarding load
transport: How much load can I transport on a set of tyres per
working hour? The Tonne Kilometres Per Hour index indicates what
your tyres can handle.
• TKPH is one of the most important factors that determine tyre life.

15. How to Calculate Tonne Kilometre Per Hour
TKPH = ( mean tyre-load ) x ( average work-shift speed )
• Mean Tyre-Load:In this case ‘mean’ means the average weight of a full and an empty
truck. We add both weights to get a total and then divide it by two to get the
average.
Mean tyre-load = ( tyre-load empty + tyre-load fully loaded ) / 2
• Average work-shift speed: The second half of the formula focusses on the actual
kilometres covered during shifts. First we need to know the amount of distance the
tyres need to cover for a full cycle. To be more plain; how much distance does a tyre
travel to haul a load from point A to point B and back to point A again. We call that a
round-trip or a cycle/shift. To get a total of the covered distance we need to multiply
this amount by the number of cycles a tyre makes per shift. In order to bring it back
to an average work-shift speed we divide the multiplied amount of distance by the
total hours of operation per shift.
Average work-shift speed = ( round-trip distance x number of cycles/shift ) / total
hours of operation/shift

16. Correct way to use tires
• Tire maintenance is a key component of an effective driver.
• It allows carriers to avoid vehicle performance issues on the road, protect their
equipment, and maximize profitability through higher uptime and fuel savings.
• 1. Ensure proper tire pressure
• During the winter, tires often run under-inflated because cold temperatures
contract air as molecules are forced closer together. This accelerates the wear on
the tire’s “shoulders” or the area at the tire’s edge between the tread and
sidewall.
• Once temperatures pick up in the summer, air molecules expand and
consequently over-inflate tires. Coupled with the worn shoulders, the sudden
climb in tire pressure increases the likelihood of blowouts.
• This is why tire pressure should be, at the very least, checked on a weekly basis—
not monthly like some truckers do

17. 2. Maintain proper wheel alignment
• Misaligned wheels can result in a range of problems that negatively impact truck
performance and tire long life.
• Following are some of the symptoms of severely misaligned tires that need
immediate attention:
• Eccentric steering wheel when driving straight
• Noticeable vibration on the steering wheel
• Irregular tread and shoulder wear
• 3. Practice tire rotation
• Tire rotation is the practice of repositioning tires to balance tire wear.
• For commercial trucks, the rear tires usually wear out faster because these vehicles
pivot on the front drive axle when making turns. This puts more friction and increases
the wear on the rear tires.
• Manufacturers sometimes include a recommended scheme for tire rotation in the
owner’s manual. An “X-pattern” can be followed to balance the wear over each tire’s
treads and shoulders.
• To do the X-pattern rotation scheme, move the right front tire to the left-rear position
and the left front tire to the right-rear position.

18. Assignement#01
• Nomenclature of off road tires
• Types of tires (All-terrain (AT),Mud-terrain (MT), Snow/Winter, Sand.)
• All-terrain (AT), Mud-terrain (MT), Snow/Winter Sand