Source: Baltic Transport Journal 4/15

1. 36 | Baltic Transport Journal | 4/2015
Tyre selection and maintenance in ports and terminals
Perhaps tyres are not the sexiest topic in the transport sector. Their importance is often omitted, which is
utmost surprising as they are the sole tangent point between vehicles and the surfaces they run on. This
means that the safety of both our privately wheeled voyages as well as port equipment bustle depends not
only on tyre quality but also on the way we treat them in daily operations.
T
yres’ gain in importance is a result
of containerisation, when standard-
isation became possible and more
efficient vehicles arrived on the
scene. Although during the first couple of
years it was the regular tyre which was used
in harbours, it soon became clear that due
to very specific factors (slow speed, rough
terrain, difficult weather conditions, heavy
loads, etc.) developments must be made.
New transport-specific tyres emerged, but
one issue remained – proper use and main-
tenance. That’s why the Port Equipment
Manufacturers Association (PEMA) quite
recently published a paper on tyre selection
and maintenance in ports and terminals.
Common and equipment-related
factors
Specific port working conditions make
freight handling equipment tyres suscep-
tible to damage to a far greater degree than
their regular counterparts will ever face on
public roads. For instance, even moving
off is sometimes a big challenge; vehicles
can lose stability which often results in tip-
ping over or problems when turning on the
spot. Port tyres are alike the normal ones
exposed to UV radiation for a longer time,
accelerating the ageing process. An uneven
surface is yet another risk factor, leading
to punctures or cuts.
Types and inflation
There are basically three types of
tyres. First, the well-known one single
metal reinforcement radial type, com-
monly used in passenger cars, light
vehicles, trucks, 4x4 vehicles. Although
its main advantages are comfort, lower
rolling resistance and better energy effi-
ciency, the radial tyre is not suitable for
many port vehicles. This is why in the
port industry cross-ply and solid tyres
are the most commonly used.
A cross-ply (bias) tyre is more durable
than the regular radial tyre, thanks to a 40
ply nylon carcass. This makes the side walls
stiffer which prevents against the ‘kiss-
ing effect’. But definitely the most reliable
and durable tyre is the solid (super-elastic)
type. It offers great stability, a long lifetime
and no puncture damage. Solid tyres are
regarded as not comfortable to use, but
their advantages, incl. also good damping
quality, compensate for the loss of comfort.
PEMA’s report on tyre selection and
maintenance also stresses out the impor-
tance of inflation level as essential in pre-
serving a good tyre condition. This has to
be checked regularly, since the majority
of tyre damage is either directly due to, or
aggrieved by incorrect inflation.
Interestingly, it is under-inflation
which causes greater damage. For instance,
a 60% correct level inflation lowers a tyre
service life expectancy by 40%, whereas
Why do they matter?
by Maciej Kniter
Tab. 1. Equipment types and key issues for tyre usage
Equipment type Key characteristics, risks and impact for tyre usage
Empty container handlers
• Pressure on the axles and tyres
• Manoeuvres with elevated loads – tyre stress
• ‘Kissing effect’ caused by sharp turns and high load
Heavy duty forklifts
• High combined weight of equipment and container – tyre pressure
• Elevation of laden containers up to 5 m – tyre pressure
Reachstackers
• Very high loads exerted on single axles – tyre pressure
• Lifting heavy loads at heights of up to 12 m – tyre pressure
Mobile harbour cranes
• Very high unladen equipment weight of up to 600 tn – extreme tyre
pressure during moves
• Equipment static for long periods – greater risk of exposure to UV
radiation, accelerating ageing of the rubber
• Crane movement often in a regular pattern along a straight line –
impact of uneven surfaces (rails, curbs) tends to be repetitively focused
on certain tyre areas
Rubber-tyred gantry cranes
• A crane can be required to turn on the spot under load and at a 90°
angle – tyre stress
• A crane does not move when its wheels are turned – tremendous
additional stress to the tyres
• Lack of movement can cause problems with UV exposure degrading
tyre rubber
• Constant loads on the same area of the tyres can lead to flat spots
Straddle carriers
• Speeds of up to 30 km/h while carrying laden containers at heights of
up to 25 m
• Hard braking can cause a ‘slip-stick’ effect where single tyres lose
surface contact – loss of vehicle stability and risk of tipping
• Selection of stiff tyre with good damping properties is crucial to
counter the ‘slip-stick’ effect
Terminal tractors
• Highest mileage of all handling equipment – high usage
• Regular stress from acceleration, braking and cornering
• Frequent travel over uneven and different surface types with potholes,
bumps and foreign objects – increases tyre wear and potential for failure
• In some climates, need for a good tyre grip on wet or slippery surfaces,
including ramps and nails
Automated guided vehicles
• Weight of batteries in electric units
• No human control – unmanned AGVs cannot avoid foreign objects
Source: PEMA
Specific port working conditions make
freight handling equipment tyres
susceptible to damage to a far greater
degree than their regular counterparts
will ever face on public roads.
Speed also affects tyres’ shape. Either too
high or too low speeds may result in a lack
of stability, causing sudden failures. The
same with heavy loads – they create a very
high bearing on the axle which is danger-
ous especially while manoeuvring, being the
main culprit behind the so-called ‘kissing
effect’ between dual tyres. Although these
are the most common threats for all tyre
types, specific vehicles have their own usage
risks (Tab. 1.).

2. Report
4/2015 | Baltic Transport Journal | 37
Report
or other foreign bodies stuck in a tyre. A
bead/rim flange should also be searched
for any deformities, chafing and damage.
In addition, the report advises to rotate
and rebalance tyres from time to time.
Alike in other businesses, time is
money in the maritime industry. Get-
ting a blowout can really ruin your day,
as freight handling equipment does not
earn a penny while it’s broken-down, not
to mention the cost of delay and repairs,
potential damage to the cargo, and in
a worst case scenario – a health & life
threat to the person behind the wheel.
All of these from a simple tyre failure!
Therefore, ‘check & maintain’ should be
the mantra of any port tyre-shoed fleet
manager. ‚
The Port Equipment Manufacturers Association (PEMA) unites equipment and technology suppliers with the chief aim to educate and promote
best practices in the maritime industry. Recently, the Association published the report Tyre Selection and Maintenance in Ports and Terminals: A
PEMA Information Paper, available on-line for public use on the www.pema.org website.
Tab. 2. Major causes of tyre damage
Item Key issues
Fitting and service
• Improper bead seating
• Bead damage
• Broken bead
Under inflation/overload
• Tyre damages
• Valve/valve caps
• Rim condition
Influences from suspension
• One-sided wear
• Wear on both shoulders
• Heel and toe wear
• Shock absorber defect
Wrong application
• Permanent overloading
• Trapped stones between twin tyres
• Cut damages
• Spot wear caused by locked wheel
(worn patch)
• Cuts caused by spinning, scuffed tread
• Excessive lateral forces
Foreign impact
• Impact break
• Cut
• Nail hole
• Hot braking drum
• Ageing
• Chemical influences
Source: PEMA
over-inflation by 20% shortens it by
approx. 15%. The inflation level affects
fuel efficiency, too. At 80% of optimum,
a vehicle will return only
75% of the ideal fuel effi-
ciency. Again, pumping
more air is not as bad as
under-inflation – 120%
pressure will give 90%
of ideal fuel efficiency.
On the other hand, over-
inflation can result in rim
deformation or tyre burst.
PEMA guides to
undergo a tyre pressure
check every two weeks,
once the vehicle has been
stopped and cooled down.
The so-called Tyre Pres-
sure Monitoring System
(TPMS) can also come
in handy as its sensors
audit the air-pressure
and temperature, provid-
ing instant feedback. Yet,
pressure control is not
the only thing to tick off; proper exami-
nation will comprise a search for any
deformities, cuts, cracks, trapped stones
Getting a blowout can really ruin your day,
as freight handling equipment does not
earn a penny while it’s broken-down, not
to mention the cost of delay and repairs,
potential damage to the cargo, and in the
worst case scenario – health & life threat
to the person behind the wheel.