Bendix Commercial Vehicle Systems SMARTIRE TPMS OPERATORS MANUAL - Manual (Page 13)

13
equilibrium (125 PSI). The tire will then be running 50°F hotter than it should be, causing more
tire wear and the potential for a catastrophic failure or tire fire.
When checked using a handheld gauge or a tire monitoring system that does not measure
operating temperature, this 10 PSI under-inflated tire can appear to be normal. When equipped
with tire sensors that mount inside the tire, SmarTire
™
TPMS measures both tire pressure and
temperature in order to provide “Temperature Compensated” pressure deviation values and
alerts. By measuring the operating temperature of a tire and comparing it to the cold inflation
pressure (CIP) value programmed into the system, the SmarTire
™
system will know what a tire’s
pressure is supposed to be in relation to its operating temperature.
The system is able to warn the driver of an under-inflated tire even if that tire’s actual contained
air pressure is at or above its CIP.
The advantages of temperature compensation are even more dramatic when a tire has a slow
leak. A tire that is constantly losing pressure will not be able to reach thermal equilibrium because
the contained air simply can not expand enough to generate the required pressure, regardless of
how hot the tire becomes. Since the leak is slow, the tire may appear over an extended period of
time to be properly inflated when it is actually dangerously under-inflated and operating well
above its temperature capacity.
As air leaks from the tire, increased side-wall flexing and rolling resistance cause the tire’s
temperature and pressure to increase. The pressure increase will soon plateau and begin to
slowly decrease while the tire’s temperature continues to increase. Eventually, the tire will
become so hot that its structure will degrade and then fail in the form of a blow-out and / or tire
fire.
2.0 TIRE MAINTENANCE
Proper tire maintenance is critically important for keeping tires rolling smoothly. When properly
maintained and inflated, tires will provide shorter stopping distances, better vehicle handling in
emergency situations and better fuel economy.
Maintenance Tips for Long Tire Life:
 Keep tires properly inflated at all times.
 Visually inspect tires for injuries prior to each trip.
 Match dual tires for size and keep pressures within 5 PSI (0.344 bar).
 Re-tread tire before wear causes excessive belt damage or fatigue.