Low tire pressure warning

[Bouldergramp]

Well, the bitter cold arrived and the low tire pressure warning showed up on the dash display. All tires were 29 psi so there was nothing to worry about. My nearby CONOCO station with free air is closed for renovation so I just drove to Boulder Nissan and let them inflate the tires. I don't think the 2018 manual explains the low tire pressure display very well. I found this:
https://www.youtube.com/watch?v=b5pwOe9k0EY

 

[LeftieBiker]

The video is a good idea, but unfortunately it encourages people to under-inflate their tires to the too-low 36psi on the label. 38-40psi is much better for all versions of the Leaf.

 

[jjeff]

The video is a good idea, but unfortunately it encourages people to under-inflate their tires to the too-low 36psi on the label. 38-40psi is much better for all versions of the Leaf.

38-40! personally, I tell people 44psi and truthfully if the max inflation of my tires were higher I'd go a couple pounds under max. One reason I tell people this is they tend to add air and then not recheck for a long time. A tire will never really gain pressure, mostly lose so I feel safe running near max inflation pressure when adding air. Note I guess if you were in a very cold area 10F, filled your tires to max a say and then drove down a mountain where it was say 75, I might change my suggestion but otherwise I feel safe at max or a couple pounds below.
What I don't understand is say I fill my tires to the max in the fall, maybe 70F. Then a couple months later it's 10F out and I recheck the tires and they are 10 or more PSI lower. I then fill the tires at this 10F to max inflation, if I then recheck the tires in the spring when it's 70F it won't be over-inflated but rather still at max or a bit below. I'd think the tires should be overinflated but they never are. I'm guessing what's going on is the tires are constantly losing just a bit of air, not a lot but just enough so the expansion from cold to hot is never really seen on the tires. It's that reason for the most part I suggest max inflation and don't really worry about it, especially on a vehicle as heavy as a Leaf(for its tire size) as I want its sidewall flexing as little as possible to avoid undue wear.
Our latest Prius tires show a 54max PSI on the tire, those I only fill to 51/52 as 54 does seem quite high. Also note I'm assuming you have an accurate tire pressure gauge as I have, if you think it might say read 5psi low or something then don't inflate to max, then you'd actually be over by 5psi which probably wouldn't be good.

 

[knightmb]

Have to agree, 36 psi or under is way too low for the vehicle. I inflated all my tires to max (44 psi) in the morning before the sun comes up and warms the tires up on one side, causing uneven inflation. I did this after the vehicle sits overnight to make sure the tires are cold. During the day, I check the tire pressure from time to time, but the cold keeps the tires from gaining much extra pressure even when driving all day. Easy, safe area is 40 psi if your tires max at 44 psi, when it gets really cold at night, you'll find your tire sensor light coming on every time if the tires were last inflated in fall/summer weather by now.

Now, having said that, if it is snowing everywhere and you need to deflate your tires for more traction, then more power to you!

 

[LeftieBiker]

I don't suggest higher pressures in Winter because of possible loss of traction in snow and ice. I used to tell people "10% below sidewall listed max pressure" and that still applies in warm weather and snowless climes.

 

[Bio-Amy]

Hi there,
Our tyre pressure lights have just come on showing 37/38 PSI but the sticker in the door recommends 36PSI. I would have thought the info in the door is correct but it seems like you all disagree, is that true?
Thanks in advance!

 

[henrydehoja]

Hi there,
Our tyre pressure lights have just come on showing 37/38 PSI but the sticker in the door recommends 36PSI. I would have thought the info in the door is correct but it seems like you all disagree, is that true?
Thanks in advance!

Welcome!

I'm not sure why your light comes ON at those tire pressures. You may have a problem with your Leaf's TPMS.

The 36 PSI tire pressure indicated on the car door is technically correct and recommended by the manufacturer. However, we (Leaf owners) typically tell people to inflate the tires to a higher pressure to improve range and efficiency. There are many threads on this forum about this topic.

 

[Bio-Amy]

Welcome!

I'm not sure why your light comes ON at those tire pressures. You may have a problem with your Leaf's TPMS.

The 36 PSI tire pressure indicated on the car door is technically correct and recommended by the manufacturer. However, we (Leaf owners) typically tell people to inflate the tires to a higher pressure to improve range and efficiency. There are many threads on this forum about this topic.

That's great info, thank you. I will check on the TPMS.
Many thanks.

 

[hradek]

Welcome!

I'm not sure why your light comes ON at those tire pressures. You may have a problem with your Leaf's TPMS.

The 36 PSI tire pressure indicated on the car door is technically correct and recommended by the manufacturer. However, we (Leaf owners) typically tell people to inflate the tires to a higher pressure to improve range and efficiency. There are many threads on this forum about this topic.

Do you live somewhere it gets cold at night? "Definition. The Ideal Gas law (PV = nRT) is an equation representing the state of a homogenous mixture of gas, which sets variables of that gas's pressure (P) times volume (V) equal to the amount in moles of that gas multiplied by the ideal gas constant (R) multiplied by its temperature (T)."

 

[cornbinder89]

Or one could just say pressure varies with temperature! Volume and moles and Redburgs (sp?) constant really don't enter into the question of tire pressure. When the air is cold the pressure drops and when warmed it rises.

 

[Drew21]

To jjeff, yes tires lose a bit of pressure over time. That's why it's recommended that you check them on some manner of schedule (lots of people say monthly). Different tires lose air at different rates, and other factors also come into play. For example, old wheels with a bit of corrosion around the bead, or with dry/hard rubber in the valve stem, will lose air more quickly. As documented here, tire pressure also fluctuates with temperature so it's a good idea to monitor more regularly as winter approaches.

As someone else recommended, the best time to check is early in the morning when the tires have not been driven or exposed to sunlight or warmer daytime temperatures. Both the tire pressure in the door jamb and the max tire pressure on your tires are in reference to a "cold" tire as described above. Assuming no damage to your tires, you have some headroom to allow for expansion as the tire temperature rises with driving, etc. I personally don't go to the max pressure on the tire, but there's no issue (outside of possible decreased ride quality) in going above the pressure shown in the door jamb.

 

[Snakebitten]

I find it interesting, and convenient, that the car does a little double beep when I'm airing up. It does so at what is reported as 33psi on the instrument cluster.
Sure makes it easy to air them all up to the same pressure, if 33 is a pressure you are happy with.

And another thing interesting about that double beep is that it confirms that the PCM is getting a signal from the tire sensor even though the instrument cluster will not populate with pressure data until you get going down the road a bit.

 

[Bio-Amy]

Do you live somewhere it gets cold at night? "Definition. The Ideal Gas law (PV = nRT) is an equation representing the state of a homogenous mixture of gas, which sets variables of that gas's pressure (P) times volume (V) equal to the amount in moles of that gas multiplied by the ideal gas constant (R) multiplied by its temperature (T)."

Hi there,
We live in a hot climate (Western Australia). Temperature at the moment is 20C at night and over 30C during the day.
We fill/check the tires in the morning so that it accounts for the heat during the day.
I'm just confused why the car dash complaints about 37PSI in the tyres when the recommended pressure is 36PSI and the tyres actually have 37PSI in them. Sounds like a fault with the settings (it's a 2022 Leaf).
Thank you all for your input

 

[hradek]

Hi there,
We live in a hot climate (Western Australia). Temperature at the moment is 20C at night and over 30C during the day.
We fill/check the tires in the morning so that it accounts for the heat during the day.
I'm just confused why the car dash complaints about 37PSI in the tyres when the recommended pressure is 36PSI and the tyres actually have 37PSI in them. Sounds like a fault with the settings (it's a 2022 Leaf).
Thank you all for your input

Is it always the same tire? Have you rotated your tires before the problem started?

 

[hradek]

Hi there,
We live in a hot climate (Western Australia). Temperature at the moment is 20C at night and over 30C during the day.
We fill/check the tires in the morning so that it accounts for the heat during the day.
I'm just confused why the car dash complaints about 37PSI in the tyres when the recommended pressure is 36PSI and the tyres actually have 37PSI in them. Sounds like a fault with the settings (it's a 2022 Leaf).
Thank you all for your input

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[JeffGamer]

I've found that every time my low tire pressure light has come on, there's turned out to be a nail in the indicated tire. Even if the PSI seems okay and the air leakage is super-slow or non-existent, the car seems to "know" there's something wrong with the tire.

 

[SteveDK]

My 2023 SV+ started saying something like "Tire Maintenance Needed," and it turned out one tire had a puncture. It was losing pressure slowly. I got a tire pump that plugs into what used to be cigarette lighter power port on old cars to boost the pressure now that Maine winter weather has arrived.

 

[jimmol]

Tire pressure plays a part in hydroplaning of tires. Equation is 9 x square root of the tire pressure. At 36 psi, hydroplaning starts at 54 mph, at 49 psi, hydroplaning starts at 63 mph.