Airlines, as well as air forces, have always been discreet about tire retreading and very discerning. In recent years the demands by airlines to retread their tires increased because of the results achieved which often exceeded those of new tires. Aircraft tires' performance is evaluated by number of landings and not by mileage as other tires. This is despite the fact that aircraft today cover a great deal of mileage on land, due to the proximity to the terminal and the increased lengths of runways. Most users do not realize that the main hysteresis of aircraft tires often occurs reaching the point of take off rather than landing, To meet the stringent requirements, aircraft retreading is produced with a very discerning QC done at all stages of production by very qualified inspectors. There is still a great dependence on the human factor, even though new automated inspection instruments are being introduced for both tires and materials. Full video of Jacob Peled's presentation is available on YouTube

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Aircraft Tire Production-New Horizons
Clemson University Tire Conference 2013
Hilton Head Island, South Carolina
April 26, 2013
Presented by:
Mr. Jacob Peled
Executive Chairman
Pelmar Engineering Ltd.
Photo: An AV-8B Harrier prepares for takeoff as another lands
CC BY Official US Navy Imagery on flickr

2. Clemson University Tire Conference 2013 2
Aircraft tire production is the only section of the tire industry wherein the
dependency on retreading is total and the requirements thereof are often
more stringent than new tires.
This chart shows various
types of tires and their
speed versus load operating
ranges. The operating range
for aircraft tires covers the
upper right hand corner,
meaning that maintenance
practices and operating
techniques that work fine for
passenger tires are not
acceptable for aircraft tires.
Any deviations to the proper
operating practices will have
immediate consequences
on the tires’ performance.
Aircraft Tire Production-New Horizons

3. The first aircraft tire was produced back in 1910 and the first retread was
produced in 1911 (by an unknown retreader, probably Dunlop themselves).
3Clemson University Tire Conference 2013
Aircraft Tire Production-New Horizons

4. There are a few smaller,
independent
manufacturers and
retreaders, but their
percentage of the market is
insignificant. This includes
Russia, Turkey, S. Korea
and Israel.
Aircraft tires are shipped
and flown all over the
world.
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There are 4 major manufacturers of aircraft tires: Goodyear, Michelin,
Bridgestone and Dunlop Aircraft Tyres Ltd., who control approximately
85% of the aircraft tire market worldwide. They are also almost the
exclusive retreaders worldwide.
Clemson University Tire Conference 2013
Aircraft Tire Production-New Horizons

5. Aircraft tire life (new or retreads) is measured by number of landings.
The average on civil aircraft is 250 – 300 landings (B737, the most common
passenger aircraft today, produced at the rate of 1.1 units per day). A
normal aircraft can reach this quota between 1 week to 3 weeks.
Military fighter plane tires do a maximum of 20 – 50 landings, depending on
aircraft and base, land or aircraft carrier.
Almost without exception, retreaded aircraft tires do significantly more
landings than new ones.
Aircraft tires lose approximately 18% of their weight between each cycle.
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Aircraft Tire Production-New Horizons

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Challenges ahead for aircraft tires
•Safer Tires
•More Intelligent Tires
•More Environmentally Friendly Tires
•More Economical Tires
•Improved Retreadability
•Increased Compatibility to Wheel
and other Equipment
•Improved Ground Performance
Clemson University Tire Conference 2013
Aircraft Tire Production-New Horizons
Photo: USS Forrestal - A-4 Landing
CC BY SA roger4336 on flickr

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Safer Tires
•Reduction of tire failure events (burst, tread separation, etc.)
•Better tire damage resistance
•Foreign Object Damage (FOD)
•Abnormal operation condition, etc.
Clemson University Tire Conference 2013
Aircraft Tire Production-New Horizons

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More Intelligent Tires
•Tire health monitoring
•Pressure, temperature, forces and road conditions etc.
•Tire damage detection
•Contribution to aircraft system control
Clemson University Tire Conference 2013
Aircraft Tire Production-New Horizons

9. •Tire Identification
Tire Identification is of significant importance especially for retreaded
aircraft tires.
It is absolutely required to have a complete history of each tire, including
repairs made and particularly retreading, which today averages 6 retreads
per tire.
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RFID (Radio-Frequency Identification) technology
Clemson University Tire Conference 2013
Aircraft Tire Production-New Horizons

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More Environmentally Friendly Tires
•Increased number of landings
•Reduction of rolling resistance
•Weight saving
•Fuel and CO2 reduction
•Use of bio-materials
•Noise reduction
Clemson University Tire Conference 2013
Aircraft Tire Production-New Horizons

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• Tire Retreading and Recycling
Retreading is by far the most friendly and
efficient tire recycling for all tires, and
particularly for aircraft tires, thus the most
economical.
• Four to Ten retreading cycles
• Increased number of landings
• 50% cost savings compared to new tires
Damaged and out of service carcasses are used
for agricultural and industrial implements,
retreaded or as is. Consequently very few
tires reach landfills.
Clemson University Tire Conference 2013
Aircraft Tire Production-New Horizons

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More Economical Tires
•Improvement in tread wear
Increased number of landings
to 500 from the average of 250
– 300 which exists today.
•Retreading
Increased number of cycles
from 3 – 6 today to 10
•Maintenance
Decreased maintenance due to
transparency of casing
condition and information
transmission.
Clemson University Tire Conference 2013
Aircraft Tire Production-New Horizons

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Improved Retreadability
Since retreading plays such a major
role in the aircraft tire industry, it is
clear that improved and faster
methods would add to the
feasibility of using one brand of
tires over the other.
Unfortunately, so far, all trials in
using pre-cured tread (cold
retreading) for aircraft tires have
been unsuccessful. This is true for
both radial and diagonal tires.
Clemson University Tire Conference 2013
Aircraft Tire Production-New Horizons

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The majority of aircraft tires are still
diagonal, and it seems that this will
remain so for the foreseeable future.
However, the number of radial sizes is
increasing.
There is no difference in
performance overall.
Computerization of
manufacturing/retreading and
particularly the test procedures,
shortens the process and improves
control.
Clemson University Tire Conference 2013
Aircraft Tire Production-New Horizons

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Increased Compatibility to Wheel and other Equipment
There is a strong reciprocal relationship between
tires and the landing gear.
Consequently, the tire manufacturers and retreaders
are often partners in breaking system’s maintenance
and replacement. Also, other components related to
landing gear and shock absorption are serviced by
the tire retreaders.
Tires are the only contact point between the airplane
and the ground and are crucial to the passengers’
and aircraft safety.
Clemson University Tire Conference 2013
Aircraft Tire Production-New Horizons

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Improved Ground Performance
The most demanding part of aircraft tires is ground performance,
especially take-offs, contrary to the common belief that landings are the
most challenging hazard to aircraft tires.
The reason is the increased weight of
fuel and the distance that needs to be
covered on the runway. With landing
the tires are very cold (-50C) which
helps avoid tread wear, unless landing
is rough or off the runway.
Clemson University Tire Conference 2013
Aircraft Tire Production-New Horizons

17. Ground performance requires:
•Anti-skid and breaking
•Normal behavior on different
contaminated runways (water, snow, ice
and more).
•Perfect steering which requires
extended deflection and large yaw
angle (up to 90°)
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Aircraft Tire Production-New Horizons

18. Final Element Model
Validation:
Final Element Testing has become popular for
aircraft tires after it was used extensively for
design and improvement for new aircraft tires.
It is possible today to carry out virtual
dynamic and static tests corresponding to
TSO (Technical Standard Order) and FAA
requirements.
Tests include load deflection of both tread and
sidewalls, footprints and contact pressure,
profile measurement, temperature build up
and the range of tests is increasing.
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Aircraft Tire Production-New Horizons

19. 2011 19
• The Tire and Rubber Industry Expert
• 45 years of Continuous Activity in the Polymer Industry
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Raw Materials
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The Pelmar Group

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Thank You
For Your Attention
www.pelmar.com
The Pelmar Group would like to express its gratitude to the people who
provided us with up-to-date data, particularly
Dunlop Aircraft Tyre Ltd. and The Goodyear Tire & Rubber Co.