Under Pressure?

[Bper]

Hi All,
I had the TPMS system light come on this morning for the first time. I thought it may be one of the TPMS wheel sensors as I could not see any flat or low tyres. So I got out the tyre gauge and the first tyre I checked was 28 psi when it should be 33 psi. 

I was surprised but reinflated the tyre and checked the light but it was still on.
So I went to the next one and again 28psi. Checked the rest and they were all well below the 33psi. When all tyres had been reinflated the check light went out which was both a relief and showed that the TPMS works.
However, I normally check the tyre pressures at least once a month but had not done so for about 5 weeks. I have not seen this level of tyre pressure drop before.

I would like to hear any thoughts and the possible causes for this to have happened.

All of the tyres had no damage, cuts, stones or nails etc.,
Tyre pressure gauge is Tiretek Premium. 

[RHYSF00]

Doubt it much to worry about. For mine it avg about 1psi a week. 

[Cyker]

Likely just the colder season - The TPMS system in my Mk4 has been reporting lower PSI, down about 5 psi now, just due to the mornings being much colder now.

It's a pretty normal drop for this time of year.

Mine get back up to pressure once I start driving and friction warms the tyres up, but the initial cold morning PSI has definitely been dropping as it's been getting colder and the sun is too low to warm my tyres as early in the morning.

[Markyswan]

2 weeks ago my warning light came on my Rav 4 and when I tested the air in the tyres all well below what they should be. The car was recently serviced as well.

[Bper]

2 hours ago, Cyker said:

Likely just the colder season - The TPMS system in my Mk4 has been reporting lower PSI, down about 5 psi now, just due to the mornings being much colder now.

It's a pretty normal drop for this time of year.

Mine get back up to pressure once I start driving and friction warms the tyres up, but the initial cold morning PSI has definitely been dropping as it's been getting colder and the sun is too low to warm my tyres as early in the morning.

Cyker thanks for the info, how often do you check your tyre pressures.

[Bper]

2 hours ago, RHYSF00 said:

Doubt it much to worry about. For mine it avg about 1psi a week. 

How often do you check your tyre pressure. 

[Bper]

1 hour ago, Markyswan said:

2 weeks ago my warning light came on my Rav 4 and when I tested the air in the tyres all well below what they should be. The car was recently serviced as well.

Hi Mark how often do you check your tyre pressures 

[Cyker]

Every time I drive - There's a display in the Mk4 that shows the tyre pressures! It's great!  It's interesting watching the PSI go up and down as I drive.

I don't know why all cars that have active TPMS sensors don't show them like this...

 

[RHYSF00]

18 minutes ago, Bper said:

How often do you check your tyre pressure. 

About once a week. 

[Bper]

43 minutes ago, Cyker said:

Every time I drive - There's a display in the Mk4 that shows the tyre pressures! It's great!  It's interesting watching the PSI go up and down as I drive.

I don't know why all cars that have active TPMS sensors don't show them like this...

 

I assume this shows the tyre pressures on each tyre ,great idea have you checked them with a gauge to see how accurate the monitoring system is.

[Cyker]

Ya, per tyre! My pump's gauge shows about 2 psi higher but tbh don't know which one is more accurate as it's quite an old footpump.

 

[Bper]

On 10/16/2022 at 10:51 PM, Cyker said:

Ya, per tyre! My pump's gauge shows about 2 psi higher but tbh don't know which one is more accurate as it's quite an old footpump.

 

Is it true that alloy wheels affect tyre pressure. 

[Cyker]

In what way? I must admit I've never heard of that!  

 

[Bper]

14 minutes ago, Cyker said:

In what way? I must admit I've never heard of that!  

 

I came across a few articles when looking for causes of tyre pressure loss. There are a few out there about alloy wheels.

Corroded Alloy Wheels - Wheels which are over 5 years old start to suffer from paint corrosion, usually starting on the inside of the wheel, once the paint has bubbled or started to flake the tyre will not seal fully on the bead, causing a deflate within days to a week.  The solution is to have your wheels fully refurbished, with a complete chemical strip and blast to remove paint or corrosion. Then the entire wheel completely powder coated. 

[Cyker]

I could see that; The alloys on my Mk1 Yaris were awful for corrosion - Hand-sized flakes of the paint were coming off; I ended up getting them acid stripped and powdercoated. (I was going to just buy some new rims but the cost of those plus the insurance hike for using non-OE alloys cost more than the powdercoating!)

But I imagine that's not limited to alloy rims - If anything I would imagine steel rims would be worse since they are more prone to rust and distortion tho'; Steel rims can also buckle and distort under impact, but alloys don't (They just crack if the impact is too strong)

 

[Stivino]

5 years?  I had mine sandblasted at 13 years old and it was to tidy up the outside, the inners were still like new.

But yes, sometimes alloys start to degrade inside but a good tyre will clean them up and use liquid rubber paint to help them seal.

[Cyker]

My steels are already corroding on the edges due to kerbing  

It's amazing how nice they looked new but how quickly they've become so manky...!

[Rhymes with Paris]

My neighbor who I bought the Yaris from told me that  the alloys were replaced under warranty within two years of his purchase from new,due to corrosion.

They are not bad now, so must have been better quality replacements.

The wheels on my old Lexus however were terrible, but did keep tyre pressure, apart from the front near side one.

I think I must be cursed by the demon of the front near side tyre though, as I have had this pressure loss on a few different cars now.

Maybe they are haunted.

[Bper]

18 hours ago, Cyker said:

I could see that; The alloys on my Mk1 Yaris were awful for corrosion - Hand-sized flakes of the paint were coming off; I ended up getting them acid stripped and powdercoated. (I was going to just buy some new rims but the cost of those plus the insurance hike for using non-OE alloys cost more than the powdercoating!)

But I imagine that's not limited to alloy rims - If anything I would imagine steel rims would be worse since they are more prone to rust and distortion tho'; Steel rims can also buckle and distort under impact, but alloys don't (They just crack if the impact is too strong)

 

I bet most motorists are not aware of this problem and I wonder why it is not widely published. Also how would you know this was the cause and what test could you do to confirm this was the problem related to tyre pressure issues.

[Stivino]

The tyre fitter should know when changing the tyres.