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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. Sho uld 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.

6. Types of tyres

7. 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.

8. 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

9. 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.

10. 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.  

11. 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

12. 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 .

13. 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

14. 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

15. 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 T ire 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.

16. 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