Without knowing the target Cold Inflation Pressure for your personal application, I can only provide some general guidelines to establish the operation of your system.
off, I recommend that TT with multi axles run a CIP equal to the tire
inflation on the side of the tire associated with the max load. This may
match the tire placard but you need to read your placard to confirm the
Motorhomes and other motorized vehicles can use the measured load on the heavier end of each axle to consult published Load & Inflation tables to learn their MINIMUM CIP. For motorized vehicles I suggest a CIP pressure of at least 10% above the minimum number shown in the tables.
Let's assume your CIP is 80 psi, as on most Load Range E tires.
One time you need to check your inflation with a good digital gauge and
confirm the hand gauge reads 80. Note the tires should be cool and not
driven on for at least two hours and not in direct sunlight to get an
Having confirmed the tires are at 80, you can
then check your TPMS monitor to see what it is reading. I would not be
surprised to see pressure variations of +/- 2 to 4 psi. Remember, TPMS
are primarily designed to warn of a loss of pressure, not to be a substitute for hand pressure
Most TPMS are set to warn when pressure has dropped 15%
from the CIP. I prefer to get a warning before tires get that low so I would set the "base level" of my Tire Traker system at about 107% of the 80 psi on my rear tires to 85 psi. This works out to 72 psi low pressure warning rather than 68 psi low if I went with the original 15% loss number.
Now my TPMS gives both a Rapid and Quick Early warning when the pressure drops 3 psi from the HOT operating pressure in about 2 to 10 minutes. You will need to learn the details of your early warning settings if you run a different brand TPMS. This early warning is not affected by my CIP or Base Level settings, as it is based on a drop from the actual hot operating pressure.
can expect to see your HOT pressure to be 10 to 20 psi above your CIP,
but this depends on your actual inflation, load, driving speed and road conditions.
also expect your operating temperature to be +10 to + 30 above ambient.
Since the sensor is external to the tire, it is cooled by the outside air
so will never read that actual internal tire temperature. So, in my opinion, if you
see +30, you need to slow down and maybe even park for 1/2 hour or so
to let the tires cool off. While there are many variables, I would not be
surprised to see external TPMS temperature readings to be 10 to 30°
cooler that internal tire temperatures so I would consider a +30° reading
to be high.
After you drive for a few weeks with your TPMS, you
will learn the variation in the readings and should not be concerned
about minor variations in the reading.
Hope this helps you understand your TPMS and how to get the information you need from it.
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