October 2017 | VehicleServicePros.com 27
» Benefits of wide base tires compared to dual tire
configurations include weight reduction, fuel efficiency,
reduced maintenance and fewer tires to inventory.
The Perils And Prevention
Of Dual Tire Imbalance
It’s common knowledge
that the right tire inflation
pressure is a major
factor in vehicle safety,
tire life, fuel efficiency
and operating costs,
say officials with Bendix
Commercial Vehicle
Systems (CVS). Less
frequently discussed
is the specific issue of
pressure imbalance in
dual tire wheelends.
Bendix CVS (www.bendix.
com) develops and
supplies leading-edge
active safety technologies,
energy management
solutions and air
brake charging and control
systems and components
under the Bendix
brand name for medium
and heavy duty trucks,
tractors, trailers, buses
and other commercial
vehicles throughout
North America.
A NEGATIVE
IMPACT
A low-pressure tire
can have a significant
negative impact, and it
doesn’t take much less
air to start accelerating
wear, says Jon Intagliata,
product manager, tire
pressure monitoring
system, Bendix. Tire
underinflation by as little
as 10 percent results in a
1.5 percent drop in fuel
economy, and underinflation
by 20 percent
results in a 30 percent
reduction in tire life.
“Add in the fact that
safety components –
ranging from brakes to
stability and collision
mitigation systems –
can’t perform to their
optimal capabilities if
tires are not operating
in their proper condition,
and the stakes
become even greater,”
Intagliata notes.
Bendix “highly recommends”
the use of a
tire pressure monitoring
system (TPMS)
to provide fleets and
drivers with real-time
information and alerts,
enabling them to
address potential failures
before they occur.
IMBALANCE
A dual tire arrangement
requires additional care,
and close attention
should be paid to keeping
both tires inflated
to the same pressure,
Bendix’s Intagliata
advises. If the pressure
between both tires
is not equal, one tire
will wind up carrying
a greater share of the
load and do more work
than the other. Because
their sizes will be slightly
different, as the tire
assembly rotates, the
smaller tire will drag,
causing premature wear.
“In short, running imbalanced
duals increases
the odds of a blowout
on the overloaded
tire and significantly
shortens tire life on the
underinflated tire,” he
says. “Industry data has
shown that the pressure
difference at which
this becomes an issue
can be as little as 5 psi.
This small difference
in pressure creates a
difference in the tire’s
circumference and causes
the smaller tire to be
dragged by the larger
tire, producing accelerated
or irregular wear.”
While addressing dual
tire imbalance is simple
enough – it’s just a matter
of setting the tires to
the right pressure, which
is routine maintenance
– noticing it in the first
place can be trickier,
Intagliata points out.
This is especially true for
the inner dual which is
masked by the outer tire,
making it very difficult
to spot a problem.
TPMS
The best tool for tracking
proper tire psi is a
tire pressure monitoring
system, says Intagliata
of Bendix. While these
vary in design, they
operate in the same
general fashion, using
sensors mounted at
each wheelend of a
tractor or trailer to
constantly measure a
tire’s pressure. If the
sensor is mounted
inside the tire, it can also
measure temperature.
Tire pressure and temperature
information is
transmitted wirelessly
and displayed on either
an in-cab display or a
technician’s handheld
device during maintenance
checks.
In the cab, most TPMS
systems will provide
pressure alerts to
drivers, he says. Some,
like the SmarTire TPMS
by Bendix CVS, can
provide temperature
compensated
pressure figures, along
with high-temperature
alerts. It also includes
a programmable alert
that will let the driver or
a technician know when
a set of duals exceeds a
set deviation in pressure
between the two tires.
To monitor trailers,
SmarTire Trailer-Link
TPMS wirelessly transmits
alerts, pressure and
temperature information
for trailers directly to the
tractor and is displayed
on the system’s TPMS
dash gauge or integrated
vehicle cluster.
“The more real-time
information and alerts
a system can provide,
the better equipped
a driver is out on the
road, and the safer
the truck becomes,”
Intagliata says.
“Simply paying attention
to the details of
correct inflation, tire
temperature and dual
tire pressure balance
can help keep vehicles
on the road and in
good operating condition,
reducing the
odds of a catastrophic
failure and improving
highway safety.”