2018 Hatchback: Constant Tire Pressure Loss, No Leak

[Bblue2005]

I got my car in January 2018. It has about 19k so far, but this year I have only driven about 2k.

Earlier this year, my TPMS came on, and would keep coming on about once a month even with me barely driving.

Americas Tire was unable to ever find a leak. Since my back left tire seemed to be the one losing air, they put on a new valve cap thinking that was the issue.

Things were good for a few months and then last night the light was back on with the tire showing 27.

They inspected it again and nothing.

Any ideas what’s happening to cause this?

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[Phy]

If you can't find a leak in the tire, you should look at the rim next. over inflate the tire off the vehicle and spray the whole thing with soapy solution.

 

[derbo904]

I got my car in January 2018. It has about 19k so far, but this year I have only driven about 2k.

Earlier this year, my TPMS came on, and would keep coming on about once a month even with me barely driving.

Americas Tire was unable to ever find a leak. Since my back left tire seemed to be the one losing air, they put on a new valve cap thinking that was the issue.

Things were good for a few months and then last night the light was back on with the tire showing 27.

They inspected it again and nothing.

Any ideas what’s happening to cause this?

Bring it to another shop.

 

[Civicboomer]

I don't think it's leaking. It's the TPMS system. Either check it through the port with the reader or reboot by disconnecting the battery and run a reset on the TPMs. See if that works.

 

[Gruber]

How fast is the pressure decreasing? How many psi per month?
So it was good for a few months? A pressure loss of 1 or two psi per month is normal. No tires are completely air tight. In addition, the pressure decreases a bit with temperature.

 

[Bblue2005]

If you can't find a leak in the tire, you should look at the rim next. over inflate the tire off the vehicle and spray the whole thing with soapy solution.

I couldn’t do that myself, do any tire shops do it for free?

 

[Bblue2005]

I don't think it's leaking. It's the TPMS system. Either check it through the port with the reader or reboot by disconnecting the battery and run a reset on the TPMs. See if that works.

But the tire was at 27 while the rest were in the 30s, so the tire is either leaking of managing to lose air quicker than the rest?

 

[Bblue2005]

How fast is the pressure decreasing? How many psi per month?
So it was good for a few months? A pressure loss of 1 or two psi per month is normal. No tires are completely air tight. In addition, the pressure decreases a bit with temperature.

Isnt it odd though to only be that one tire that is constantly low while the rest are okay?

 

[fjrman]

The cap is not air-tight. It's there to keep dirt out of the air valve, not to keep air in the tire.

However, you say a new cap slowed the leak for a while. That would suggest the air valve has a slow leak.

Maybe you meant they replaced the air valve rather than the cap.

 

[Bblue2005]

The cap is not air-tight. It's there to keep dirt out of the air valve, not to keep air in the tire.

However, you say a new cap slowed the leak for a while. That would suggest the air valve has a slow leak.

Maybe you meant they replaced the air valve rather than the cap.

I would think they just replaced the cap because it was free. So next step is replace the valve too?

 

[fjrman]

Info for the typical tire air valve, stem, etc.

https://en.wikipedia.org/wiki/Schrader_valve

 

[tacthecat]

Easy way to check if it's leaking around the valve/stem is to mix up a little soapy water (dish detergent works great) and spray it on the valve with the cap removed. Also be aware that a nail in the tire is also still a possibility. They are hard to detect and can be wheel position sensitive. I chased one for months because "sometimes it did, sometimes it don't"!

 

[Bblue2005]

Info for the typical tire air valve, stem, etc.

https://en.wikipedia.org/wiki/Schrader_valve

It sounds like it is easy to replace yourself or no?

 

[Bblue2005]

Easy way to check it it's leaking around the valve/stem is to mix up a little soapy water (dish detergent works great) and spray it on the valve with the cap removed. Also be aware that a nail in the tire is also still a possibility. They are hard to detect and can be wheel position sensitive. I chased one for months because "sometimes it did, sometimes it don't"!

Since I had America’s tire do an inspection twice, I’d hope it wasn’t missed both times. But I can try the soap water and see what happens.

 

[skottharrison]

No, replacing the valve stem cannot be done yourself... it involves removing the tire, pulling the valve stem out and I believe gluing/cementing a new valve in.

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