Your
tires play a key role in ensuring your safety while you're on the
road. Yet even brand new tires can become a liability if you don't
keep them properly inflated. Underinflated tires reduce vehicle
control, especially when making turns. In addition, underinflated
tires wear out much more quickly and can lead to fuel economy
reductions as great as five
percent.
In
the past, car owners had to painstakingly measure tire pressure
themselves. Fortunately, virtually all cars manufactured today
accomplish this task automatically using a tire pressure monitoring
system, or TPMS. If you would like to learn more about this vital
component, keep reading. This article outlines three key things to
know about your car's TPMS.
1.
Congress Made TPMS Mandatory in New Cars
As
noted above, TPMS technology allows your car to independently monitor
tire pressure levels. If any of your tires become underinflated by 25
percent or more, the system provides a warning, usually in the form
of a dash light going on. This light remains on until the
underinflated tire has received additional air.
TPMS
offer such an accurate and reliable way of monitoring pressure that
Congress made them mandatory as part of the TREAD Act. All cars and
light trucks manufactured since September 1, 2007, have contained
TMPS. A study conducted five years after the TREAD Act went into
place found that TMPS had led to a 55.6
percent reduction in
the chances that a car suffered from one or more
significantly underinflated tires.
2.
Two Types of TMPS Exist
Tire
pressure monitoring systems break down into two main categories:
direct and indirect. Direct TMPS contain special sensors mounted
inside of the wheels themselves. These sensors use a special
component known as a pressure transducer to take periodic readings of
the pressure level. The sensor then sends this information to the
car's computer using radio frequency technology.
Indirect
TPMS take a much different approach. An indirect TPMS makes use of
the wheel speed sensors used by a car's antilock brake system. As a
tire's pressure level drops, its speed of rotation also changes.
Thus, by monitoring the speed of each of your wheels, an indirect
TPMS can infer when pressure levels have dropped below an acceptable
threshold.
Direct
TPMS remain more common than indirect TPMS, owing largely to
reliability issues regarding the first few generations of indirect
systems. Older indirect TPMS often struggled to identify insufficient
pressure when all four wheels were affected to the same extent. In
that case, wheel speeds would remain relatively identical to one
another, even though pressure was excessively low.
Newer
indirect systems have corrected such problems. As a result, more
manufacturers have begun using indirect TPMS. Generally speaking,
Asian- and European-made cars contain indirect TPMS, while
American-made cars more commonly use direct TPMS.
3.
Direct Sensors Require Periodic Replacement
Direct
TPMS have a distinct lifespan, usually lasting between 5 and 7 years.
The precise lifespan relates directly to the number of miles driven
by the vehicle. Simply put, the more you drive, the more frequently
the system sends signals to your car's computer. And the more
frequently a TMPS sends information, the more quickly its batteries
run down.
In
other words, battery failure remains the most common source of TMPS
failure. In some cases, a TMPS sensor may also fail due to corrosion
on the valve stem. This issue only affects those sensors containing
aluminum stems. For this reason, rubber stems have become an
increasingly popular choice.
Most
mechanics recommend changing your TPMS sensors every time you change
your tires. For more information about how to determine whether your
TPMS continues to work correctly, please contact
the wheel and tire experts at
Radial Tire Service.
