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2010 2011 BMW 5 Series Forum F10 BMW 5-Series (F10) Forums General 5-Series Sedan and Wagon (F10 / F11) Forum Pressure differential to activate TPMS??
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      08-16-2011, 11:16 PM   #1
JAGD
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Pressure differential to activate TPMS??

My 535 was sitting in the garage for 2 weeks while we were on vacation. When I started it up and drove for about 2 blocks, the TPMS activated with a warning of low pressure in the right front tire. I checked all tires and found the right front to be at 32psi which is 3psi (8.6%) below the recommended pressure of 35psi. All the others were about 6% below recommended pressure. My gauge is very accurate so I am not worried about the numbers. The BMW owners manual states that the system activates when "there is a major drop in inflation pressure", but does not define major drop. I am going to infer that whether you measure in BAR, PSI, KPA, etc any loss of 8% or greater will activate the system. Any thoughts?
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      08-17-2011, 12:05 AM   #2
1HOT BMR
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My TPMS does the same thing and activates at around 4 lbs below rec inflation - inflate, reset, and you are good to go. Sport mode does not engage when TPMS has a warning going on.
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      08-17-2011, 09:39 PM   #3
mspeasl
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Spec is +/- 3 pounds.
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      08-17-2011, 10:33 PM   #4
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The TREAD act requires that the sensors alert NLT 25% below the set pressure.

Some systems (BMW for one) tend to alert much sooner - but - it alerts not according to the recommended pressure, but at the pressure that the system was reset to.

So, if the dealer initially set the pressure to 42psi (not uncommon) then the system would be required to lert at around 32psi.

In my experience with E90 sensors, you'll get an alert around 20% low.

Remember that the sensors are only intended to alert you to a potentially unsafe tire pressure and is not intended to replace your periodic checks.
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