TPMS Sensors - Page 18 - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

Tcoat · 05-10-2018, 08:46 AM

Quote:

Originally Posted by new2subaru

From what I've read you get a dash light when the tire(s) are 25% low.

(25% LOW ON AIR)

What are the point of these things again?

I have had mine go off with as little as 3 or 4 PSI below the 35 that they are set for. Even had them triggered by a cold night but when they warmed up they were bang on 35 so not sure where this 25% number came from.

churchx · 05-10-2018, 08:59 AM

Too lazy to search manuals and in manual (my, made in late 2013, has no TPMS, so probably also newer manual needed), but is TPMS light triggered by absolute pressure? Wasn't it "if tire pressure is lower then in other tires"?

Vital · 05-10-2018, 09:22 AM

Quote:

Originally Posted by churchx

Too lazy to search manuals and in manual (my, made in late 2013, has no TPMS, so probably also newer manual needed), but is TPMS light triggered by absolute pressure? Wasn't it "if tire pressure is lower then in other tires"?

Not sure about other countries, but in USA its required to have TPMS now. Yes, TPMS is triggered by pressure being low generally when tires are 25-26psi. It can also be triggered when temperatures get very low.

wparsons · 05-10-2018, 11:50 AM

Quote:

Originally Posted by Tcoat

I have had mine go off with as little as 3 or 4 PSI below the 35 that they are set for. Even had them triggered by a cold night but when they warmed up they were bang on 35 so not sure where this 25% number came from.

I find the magic number on mine is ~28psi. I typically drop my tire pressure at track days to about 28psi cold and don't get the light all day until the drive home when the tires are actually cold again.

Quote:

Originally Posted by Vital

Not sure about other countries, but in USA its required to have TPMS now. Yes, TPMS is triggered by pressure being low generally when tires are 25-26psi. It can also be triggered when temperatures get very low.

They're always triggered by pressure being too low, temperature does not trigger them directly. Temperature dropping will cause the pressure to drop though.

DarkSideFRS · 05-10-2018, 12:01 PM

can we go to a track if the low air indicator is on? getting my rims soon and debating if i should transfer over the TPMS. I am leaning to no

new2subaru · 05-10-2018, 08:54 PM

Quote:

Originally Posted by Yoshoobaroo

To keep people from driving around on 10PSI, which I see regularly on my commute still.

Some cars give you a readout on the on board computer for each wheel. Why we can't have that in every car is beyond me. BMW even got rid of individual readouts around 2010, apparently people were too confused

lol I would sign up for those! They make sense and it would be a fantastic tool.

new2subaru · 05-10-2018, 08:56 PM

Quote:

Originally Posted by Tcoat

I have had mine go off with as little as 3 or 4 PSI below the 35 that they are set for. Even had them triggered by a cold night but when they warmed up they were bang on 35 so not sure where this 25% number came from.

Read it on the net. I thought 25% was the magic number?

Tcoat · 05-10-2018, 08:57 PM

Quote:

Originally Posted by new2subaru

Read it on the net. I thought 25% was the magic number?

Maybe some are. I don't know. All I know is that mine will come on well under 25%

wparsons · 05-11-2018, 08:51 AM

Quote:

Originally Posted by DarkSideFRS

can we go to a track if the low air indicator is on? getting my rims soon and debating if i should transfer over the TPMS. I am leaning to no

Why wouldn't you be able to go on a track with the light on? The sensors are a requirement because people (in general) suck and will drive around with like 15 psi in a tire and not notice. If you're that unaware on a track, you probably shouldn't be on it in the first place.

I run my current tires at about 34 PSI hot (AD08R's seem to love lower pressures), which typically means ~28psi cold. At the start of the day or when I'm driving home I'll have the light on.

DarkSideFRS · 05-11-2018, 02:00 PM

Quote:

Originally Posted by wparsons

Why wouldn't you be able to go on a track with the light on? The sensors are a requirement because people (in general) suck and will drive around with like 15 psi in a tire and not notice. If you're that unaware on a track, you probably shouldn't be on it in the first place.

I run my current tires at about 34 PSI hot (AD08R's seem to love lower pressures), which typically means ~28psi cold. At the start of the day or when I'm driving home I'll have the light on.

i have never been on a track, but i want to.. i know some have exhaust db limitations and some check for CELs... and since some check for CELs, i figured low air light as well... just making sure...

Tcoat · 05-11-2018, 02:49 PM

Quote:

Originally Posted by DarkSideFRS

i have never been on a track, but i want to.. i know some have exhaust db limitations and some check for CELs... and since some check for CELs, i figured low air light as well... just making sure...

The tire light is not a CEL so all is good.

timurrrr · 06-21-2019, 04:22 AM

Just to give folks more ideas / options, want to share my experience.
When I ordered my wheels at America's Tire, they said they can clone the IDs from my TPMS sensors to a set of new TPMS sensors, and then I can swap between sets of wheels with no problems.

The line on the receipt says
SCH 33520 TQ12 T10 315/433 EZ TPMS SENS SNAP IN 33520
— I presume these are Schrader EZ-sensor.

They used Bartec Tech400Pro to do the ID cloning.

Sadly, I couldn't confirm if the sensors worked afterwards, since the wheels didn't fit, but that's a different story.

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05-10-2018, 08:59 AM	#240
churchx Senior Member Join Date: Mar 2015 Drives: 2014 GT86 Location: Latvia, Riga Posts: 4,333 Thanks: 696 Thanked 2,085 Times in 1,436 Posts Mentioned: 53 Post(s) Tagged: 1 Thread(s)	Too lazy to search manuals and in manual (my, made in late 2013, has no TPMS, so probably also newer manual needed), but is TPMS light triggered by absolute pressure? Wasn't it "if tire pressure is lower then in other tires"?

05-10-2018, 12:01 PM	#243
DarkSideFRS Banned Join Date: Apr 2017 Drives: 2013 pearl white FR-S Location: Socal Posts: 536 Thanks: 39 Thanked 191 Times in 124 Posts Mentioned: 3 Post(s) Tagged: 0 Thread(s)	can we go to a track if the low air indicator is on? getting my rims soon and debating if i should transfer over the TPMS. I am leaning to no

06-21-2019, 04:22 AM	#250
timurrrr Senior Member Join Date: May 2019 Drives: 2022 GR86 Location: Between Sonoma and Laguna Seca Posts: 1,707 Thanks: 2,129 Thanked 1,297 Times in 718 Posts Mentioned: 30 Post(s) Tagged: 1 Thread(s)	Just to give folks more ideas / options, want to share my experience. When I ordered my wheels at America's Tire, they said they can clone the IDs from my TPMS sensors to a set of new TPMS sensors, and then I can swap between sets of wheels with no problems. The line on the receipt says SCH 33520 TQ12 T10 315/433 EZ TPMS SENS SNAP IN 33520 — I presume these are Schrader EZ-sensor. They used Bartec Tech400Pro to do the ID cloning. Sadly, I couldn't confirm if the sensors worked afterwards, since the wheels didn't fit, but that's a different story.

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