TPMS - How To Create A Baseline Reading

[addysdaddy]

I could not find a way to create a "baseline" tire pressure on my G70. On my wife's GLC300, you cold fill the tires to the desired pressure and go into the pressure reading menu - where you then hit a "set" button to establish a baseline. Should the pressure drop 3-5 lbs or more from that mark, you get an alert. There doesn't seem to be a comparable function on the G70. The manual also doesn't say how many lbs it takes to trigger an alert. Can anyone clarify?

 

[NLJ]

Don't think there is. On my Mitsubishi, a 4psi difference between tires will cause the TPMS to go off.

 

[addysdaddy]

So there is no way to create a baseline reading AND we don't know how much the pressure loss is before tripping the alert? Seems surprising for such a well thought out vehicle.

 

[joschneider]

So there is no way to create a baseline reading AND we don't know how much the pressure loss is before tripping the alert? Seems surprising for such a well thought out vehicle.

No way to set a baseline. Pressure loss should be 4-5 lbs before alert but I don’t know that 100%. The default baseline is what is set for the load and available tires and can be found on the door. Since that was well thought out, I don’t think they want customers creating their own

 

[EdP]

So there is no way to create a baseline reading AND we don't know how much the pressure loss is before tripping the alert? Seems surprising for such a well thought out vehicle.

Mine trip at 29 psi on my last 3 cars. Setting a baseline would be OK if there was a minimum and you like to keep pressure at higher than the sticker. The government just says you have to be over a minimum pressure and they comply. I don't know what the exact spec is. If allowed to set a baseline low, someone will set it at whatever makes the light go out and never bother to add air.

Reality is, 98% of drivers have no idea what they should set as baseline so Genesis keeps cost down by not having it.

 

[addysdaddy]

Mine trip at 29 psi on my last 3 cars. Setting a baseline would be OK if there was a minimum and you like to keep pressure at higher than the sticker. The government just says you have to be over a minimum pressure and they comply. I don't know what the exact spec is. If allowed to set a baseline low, someone will set it at whatever makes the light go out and never bother to add air.

Reality is, 98% of drivers have no idea what they should set as baseline so Genesis keeps cost down by not having it.

Well in a weird way I understand that logic - haha. Thanks for the explanation. Set my pressure to +1 over what's on the door.

 

[nellie1289]

On this topic my low pressure light came on today as I left outside and it was cold. 29psi. I drove around and it came back to 32 as it warmed up. But light won’t go out. So I filled all tires to cold 35. Right front light still on. Do I need to drive it farther. I did a hot lap around hood to see if it would go out. Now all tires are at 36 and light still on.

 

[EdP]

On this topic my low pressure light came on today as I left outside and it was cold. 29psi. I drove a sound and it came back to 32 as it warmed up. But light won’t go out. So I filled all tires to cold 35. Right front light still on. Do I need to drive it farther. I did a hot lap around hood to see if it would go out. Now all tires are at 36 and light still on.

Probably a bad sensor. Should have gone off by now.

 

[Mr. Incredible]

NHTSA regulations require the system to trigger if there is a 20% drop from recommended pressure or a difference of 20% between the lowest and highest readings of the 4 tires.

so at 36psi the system will trigger when any tire drops 7psi or there is a 7psi difference between the lowest and highest readings.

 

[addysdaddy]

NHTSA regulations require the system to trigger if there is a 20% drop from recommended pressure or a difference of 20% between the lowest and highest readings of the 4 tires.

so at 36psi the system will trigger when any tire drops 7psi or there is a 7psi difference between the lowest and highest readings.

Good to know - thanks for that. I'm assuming the recommended pressure is what is written on the inside of the driver's door.

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[Toddasaurus]

On this topic my low pressure light came on today as I left outside and it was cold. 29psi. I drove around and it came back to 32 as it warmed up. But light won’t go out. So I filled all tires to cold 35. Right front light still on. Do I need to drive it farther. I did a hot lap around hood to see if it would go out. Now all tires are at 36 and light still on.

Low pressure light still on today?

 

[Mr. Incredible]

Good to know - thanks for that. I'm assuming the recommended pressure is what is written on the inside of the driver's door.

Yes. That is correct.

but if you run above that, like some of us, the second part of the equation comes into play. So it’s an either/or situation.

I run 37 front 38 rear in g80 sport, which is 4lbs above recommended because to me the ride was too soft and because I carry some heavy gear (music instruments) daily in my trunk.


since I am above recommended my alert comes on when one tire is at 30-31 psi, which is about 25% below the others vs 27-28psi. But it will also come on when all tires are below 28psi.


I’ve tested it by airing up and down the tires, because like you I was used to a system that allowed me to set a baseline.

 

[addysdaddy]

Good to know - thanks!

 

[nellie1289]

Low pressure light still on today?

It went out after a 1.5 mile drive.

 

[pmckechnie]

One thing that has not been brought up is the pressure change with the temperature goes up and down.
If you set your pressure at 36 psi and the temperature is 40 deg at 7:00 am, and you go to work and when you get home at 5:00 pm and the temperature is 80 deg, then your pressure in the tires is now 40 psi.

In other words, for every 10 deg of change , the temp will increase or decrease 1 psi.
So What should I set my tire pressure to?

One thing for sure, I am not going to change the tire pressure 2 or 3 times a day.

 

[Mr. Incredible]

One thing that has not been brought up is the pressure change with the temperature goes up and down.
If you set your pressure at 36 psi and the temperature is 40 deg at 7:00 am, and you go to work and when you get home at 5:00 pm and the temperature is 80 deg, then your pressure in the tires is now 40 psi.

In other words, for every 10 deg of change , the temp will increase or decrease 1 psi.
So What should I set my tire pressure to?

One thing for sure, I am not going to change the tire pressure 2 or 3 times a day.

the recommended pressure is based of ambient temp of 70°, the tire temp, not the outside temp. but consider if the car has been sitting 4-6 hours the tires will match the outside ambient air temps.


so if you set the psi when it is 50° deduct 2 psi

if you set it when it is 80° add 1 psi.


add or subtract 1 psi for each 10° above or below 70° when you test the pressure.

 

[pmckechnie]

Thanks Mr. Incredible. That is what I was trying to get across.

Also keep in mind that if the car is outside and the sun is shinning on one side, that side will
need a lower pressure than the other side. How much, I don't know. I use a temperature sensor
that you just have to point at the tire to get the temperature.

 

[EdP]

Thanks Mr. Incredible. That is what I was trying to get across.

Also keep in mind that if the car is outside and the sun is shinning on one side, that side will
need a lower pressure than the other side. How much, I don't know. I use a temperature sensor
that you just have to point at the tire to get the temperature.

That will give a false reading too. You are getting the surface of one side of a tire that is mostly shaded. For accuracy you'd need to drill a small hole and insert a probe.

In shirt sleeve weather I just get them to 35 psi. I really don't see any difference from 34 to 36. Close enough for me.

 

[Mr. Incredible]

That will give a false reading too. You are getting the surface of one side of a tire that is mostly shaded. For accuracy you'd need to drill a small hole and insert a probe.

In shirt sleeve weather I just get them to 35 psi. I really don't see any difference from 34 to 36. Close enough for me.

you’re joking about drilling a hole right?


all you need is the right tool,

cheap version:

https://www.amazon.com/dp/B074WKVG6...colid=M0VQW9LJ3GEX&psc=1&ref_=lv_ov_lig_dp_it


racing/better/correct version:

Amazon.com: NEW LONGACRE DIGITAL TEMPERATURE COMPENSATED TIRE PRESSURE AIR GAUGE, 0-100 PSI, READS 0.1 PSI, RACING, MODIFIED, LATE MODEL, STREET STOCK, SPRINT CAR, MIDGET, MICRO MINI GO KARTS MOTORCYCLES KARTING: Automotive


both of these tell you the air temp in the tire, the bottom one will correct the pressure to the correct pressure for the temp, obviously only if the pressure is higher than it should be, it had a air release valve, if it is too low you would add air, then use this to properly adjust.

 

[EdP]

you’re joking about drilling a hole right?

cheap version:

https://www.amazon.com/dp/B074WKVG6...colid=M0VQW9LJ3GEX&psc=1&ref_=lv_ov_lig_dp_it

The hole is for accuracy. I'm a "big picture" thinker. Others can come up with minor solutions like a way to patch the hole with duct tape.

If I had a car with no sensor I'd go for the one shown. Would be very nice to have, especially in crappy winter weather.