Factors affecting tyre life-1.ppt

Fuel Efficiency: The steel braced tread and the radial casing results in less
rolling resistance and heat build-up while the tyre is in motion.
This combination translates to lower fuel bills and extended tyre life
Lower cost per kilometer: The Radial construction of Regal tyre reduces
friction and heat build-up inside the tyre, increasing the casing durability.
This combined with radial construction proves increased tyre life advantage
and thereby lower cost per kilometer.
In addition, the retreadability of Regal tyres is a significant cost saver
Road Holding: A Regal radial tyre has perfect foot print and therefore good
road grip. Its sidewalls and tread work independently. Its contact patch in
the ground is not affected, thus ensuring better road handling resulting
enhanced dependability and performance
Comfort: By its construction, a radial tyre deflects under load and this
flexibility helps cushion shocks and gives smoother ride
Reduced downtime: The steel belts help protect against punctures
Repairability: Proper repair within specifications helps to put the tyre back
in service, therefore lowering cost

KEY FUNDAMENTALS
THAT COSTS MONEY

Low Air Pressure: This is the number one (alongwith the improper
alignment) tyre maintenance issue in transportation industry. The purpose
is to maintain a recommended fleet inflation pressure based on application.
Variance of more than 10 psi could cost almost half the tyre life
Valve caps: Slow Air loss is the primary result of damaged or missing valve
caps. Properly installed and maintained valve caps acts as a secondary air
seal. The basic function of the valve cap is to prevent dust damaging the
valve core containing a rubber or plastic seal.
Mismatch of Air pressure in duals: The target is to maintain dual tyres with
equal pressure and within the range of 10 psi. Mismatched dual pressure
can lead to permanent irregular wear which can develop and therefore can
potentially be a cause of premature tyre removal. The matched tyre can also
get affected by this difference.
Mismatched height in duals: The recommended tolerance of matching duals
is 12.7 mm in Overall diameter. If the tyre is matched beyond the tolerance,
it could lead to a loss of mileage of close to 5 – 20% of tread life.

Over Inflation: Again, the goal is to maintain recommended inflation
pressure specified for the fleet operation and within tolerance of 10 psi.
Over inflated tyres are more likely to be damaged by impact breaks and
accelerated wear.
Irregular wear: Proper Air pressure maintenance, and minimizing vehicle
mis-alignment can reduce can eliminate irregular wear. Irregular wear can
also cause premature tyre removal leading to loss of tread life which could
be as high as 50%

IMPORTANT FACTORS
AFFECTING FUEL ECONOMY

When a vehicle travels from point A to B, there are number of factors that
could contribute to the amount of fuel it could consume. Tyres are just one
of the many factors.
As each tyre on a vehicle rolls down on the road, it creates a drag force. It is
composed of energy loss created by deflection of sidewalls and
compression and deformation of tread in the foot print on the road. This
drag is called as Rolling Resistance and can be measured in the laboratory.
Other factors contributing to the fuel efficiency which includes,
Aerodynamics and speed, load, vehicle alignment, inflation pressure and
driving style.

Aerodynamics and speed: A vehicle’s aerodynamics and its traveling speed
have an extremely large effect on how much fuel is consumed. The force
created by the aerodynamic drag of a vehicle goes up exponentially with
the speed of the vehicle. Tyre rolling resistance increases with speed, but
they are in smaller proportion percentage of the total drag in a vehicle as
speed increases.
Load: A heavily loaded truck will consume more fuel than a lightly loaded
truck. As an example, think of the extra fuel that you might use when taking
the entire family with luggage on a vacation as compared to the fuel you
might consume with you as a driver and no passengers.
For a truck, the golden thumb rule is that for every 10000 Kgs increase, fuel
economy drops by 5%
Wheel alignment and Inflation pressure: If any of the wheels on a 18
wheeler Tractor & Semi Trailor is misaligned, the total drag on the vehicle
increases. There is a greater scrub of the tyres against the road surface
especially when the tyres of Tractor & Semi Trailor are not tracking parallel
to the direction of travel.

Driving Style: The driving habits or style of a driver can have a large
influence on the amount of fuel consumed. Aggressive drivers can negate
many of the gains obtained from investments in fuel efficient tyres and
engines, aerodynamic devices or synthetic lubricants. With today’s
technology, it is possible to measure the amount of fuel an engine would
consume over a period of time and programs can be set up to reward the
driver for fuel efficiency
Other Factors: Ambient air temperature, weather conditions, road surfaces
(gravel, asphalt, concrete) and terrain (flat, hilly or mountanious) are
environmental factors that are impossible to control, but have direct effect
on fuel consumption.

Summary: Each of the wheel positions contribute to a portion of the total
rolling resistance. The Drive and Trailor axle tyres account for close to 85%
of total rolling resistance. Efforts should be made to follow correct
application to fit.
Most of the gains in fuel efficiency can be obtained from the tread of the
tyre, from the tread compound, tread design and/or the tread depth.
Research shows that the tread contributes to over half of the rolling
resistance.
It is important to keep the tyres properly inflated. Fuel economy falls
sharply when tyres are under-inflated.
If a rolling resistance improvement is made with the tread only, then the
improvement is zero as the tread is wornout.
If a rolling resistance improvement is made in the casing components of the
tyre, then the improvement will remain throughout the tread life of the tyre
and also post retread.

Seasonal and Climatical conditions
Factors Affecting Tyre Life
Unavoidable

Effects of air temperature on tyre life
Ambient temp  C Tread Mileage
15
20
25
30
35
40
45
Unavoidable
200
160
140
100
80
60
40

Type of roads used
Highways, Rural, Urban lanes, Winding
roads, Un-paved etc..
Delivery yards
On/Off road haulage Quarries, Tips,
Transfer stations, etc..
Parcel Delivery work
Fare stage buses
Unavoidable
Type of Work

Maintenance
Alignment
Balancing
Inflation Pressure
Driving methods
Fitting
Avoidable
Factors

Condition of wheel assembly
Wheel nuts tightened to the correct
torque setting with proper fixings
Tyre has no obvious damage
Correct twinning
Oil, Petrol, Diesel contamination
Regular vehicle maintenance
Avoidable
Maintenance

Toe in - Toe out
Caster
Kingpin inclination
Camber
Thrust angle
Axle parallelism and perpendicularity
Avoidable
Alignment

Balancing
Single plane /
Static
Static balance
measures only
“up and down”.
Double plane /
Dynamic
Dynamic balance
measures from
“side to side”.
Avoidable

Today's automobiles are designed to ride
smoothly and handle safely. Unchecked,
excessive wheel vibration can result in:
Excessive tyre wear
Damage to suspension & steering parts
Unsafe steering
Handling
Unsafe driving conditions
Avoidable
Balancing

Under-inflation
Vehicle is not overloaded
(but consequently the tyres are)
Over-inflation
Avoidable
Inflation Pressure

% Under
inflation
Loss of Life Sample on
1,00,000 Kms
10% 13% 13,000
15% 19% 19,000
20% 26% 26,000
25% 39% 39,000
30% 52% 52,000
40% 66% 66,000
Avoidable
Inflation Pressure

At a constant speed of 100
kmph Rolling resistance
contributes to consuming
100 HP
Air resistance contributes
to consuming 160 HP
Rolling + Air resistance
contributes to 260 HP
Avoidable
160
260
100
0
50
100
150
200
250
300
Rolling
Resistance
Air
Resistance
Rolling + Air
Resistance
Horse
Power
Horse Power required

6.5
5.5
4.5
0
1
2
3
4
5
6
7
30 50 70
Speed
KMPL
Avoidable
Speed is directly
proportionate to fuel
efficiency
Increase in speed reduces
fuel efficiency
Fuel Efficiency also drops if
tyres are overloaded
Fuel efficiency decreases
with low inflation pressure
than recommended, as the
rolling resistance increases
Fuel Economy

Avoidable
2.5
4.5
6.5
0
1
2
3
4
5
6
7
KMPL
30 50 70
Tread Wear %
The fuel efficiency increases
with the tread wear
Especially observed in block/
lug pattern tyres with higher
tread depth
Due to the inherent property
of tread block/ lug shuffling,
some energy is lost to
overcome the resistance. As
the tread wears, the energy
loss is lower
Tread Wear Vs Fuel Economy

Ref 40,000 Kgs
30,000 Kgs 4.40% savings
20,000 Kgs 8.80% savings
Empty 21.1% savings
1. While most users cannot afford to cut loads to save fuel, there are
ways to convert non paying load into payload, by reducing unloaded
vehicle weight
2. Lighter weight accessories and tyres (like low profile) can help
increase revenue producing capacity without adding to gross weight
Avoidable
Load Vs Fuel Economy

Rapid acceleration
Heavy braking
High speed cornering
Impact damage
(run over pot holes, kerbs, etc…)
Avoidable
Driving Habit Vs Fuel Economy

Correct tyre size for tyre rim
Suitable tyre lubricant used
No damage to bead area during fitting
Tyre fitted concentrically on its rim
Always check rim centering line to
confirm correct fitment
Avoidable
Fitment Practice

Unavoidable
• Climatic & seasonal
conditions
• Type of work
• Types of road
Avoidable
• Maintenance
• Alignment
• Balance
• Pressure & loads
• Driving methods
• Fitting

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