Tyre Pressures

[MakaveliX]

I regularly check my tyre pressures weekly with a decent ( and expensive ) electronic gauge. Tyres are Michellin PS5.

All of my tyres seem to hold air very well except one tyre which was plugged after getting a puncture a few months ago.

I pumped the tyre up to 33PSI 5 weeks ago, and today it is 31PSI. All of the others are the same as they were 5 weeks ago, this seems to be a regular thing, the tyre I had plugged seems to lose slightly more air than the rest. Did do some reading and apparently it's completely normal to lose upto 2PSI per month, but why is it only one tyre seems to lose air ?

Could the fact the tyre has been plugged have something to do with it or not ?

Thanks

[drmotorsport]

Yes.

Also pressure will vary with ambient temperature and sunlight exposure

[P. ONeill]

There are a number of reasons why you could be losing pressure but I would be looking at the plug first.
I’d also be checking the pressure more often than ever five weeks.

[MakaveliX]

drmotorsport said:

Yes.

Also pressure will vary with ambient temperature and sunlight exposure

Thanks for the reply

Yes I am aware that for every 10c in different temperature it can affect the pressure by 2PSI.

As said I have closely monitored the tyres for a few months usually in the morning before driving anywhere whilst it's cold outside. And the one that has been plugged always tends to be slightly lower

[MakaveliX]

P. ONeill said:

There are a number of reasons why you could be losing pressure but I would be looking at the plug first.
I’d also be checking the pressure more often than ever five weeks.

As said in my first post, I check my pressures once a week.

[Dave.]

Get some soapy water and wet the valve stem, the base, the inside and outside rim of the tyre, and around the repair, you’ll soon see where the leak is.

[MakaveliX]

Dave. said:

Get some soapy water and wet the valve stem, the base, the inside and outside rim of the tyre, and around the repair, you’ll soon see where the leak is.

If its only losing 2psi every month then surely it would be very difficult to find any source of a leak by using that method?

[stevieturbo]

MakaveliX said:

If its only losing 2psi every month then surely it would be very difficult to find any source of a leak by using that method?

Perhaps, but you stand more chance than listening for a leak.

Really, it could be the wheel, the tyre, the tyre seal against the wheel, the valve, the schrader valve inside the valve body....could be the plug.

All, or none of the above.

[P. ONeill]

MakaveliX said:

P. ONeill said:

There are a number of reasons why you could be losing pressure but I would be looking at the plug first.
I’d also be checking the pressure more often than ever five weeks.

As said in my first post, I check my pressures once a week.

Apologies, I saw the part where you mentioned 5 weeks and assumed.

I’d be looking at the plug but because it’s losing so little it may not be obvious to anyone who checks it. I’ve been there.

[MakaveliX]

stevieturbo said:

Perhaps, but you stand more chance than listening for a leak.

Really, it could be the wheel, the tyre, the tyre seal against the wheel, the valve, the schrader valve inside the valve body....could be the plug.

All, or none of the above.

Fair enough.
Do I need to be concerned about this or not ?

[Dave.]

MakaveliX said:

Fair enough.
Do I need to be concerned about this or not ?

Maybe, maybe not.

If the valve’s not seated correctly it could get worse over time. (Unlikely)

If it the tyre’s not sealed against the rim correctly, one awkward pothole could debead it altogether. (Again, unlikely)

If it’s the previous repair, wouldn’t you want them to have done a proper job?

[MakaveliX]

Dave. said:

Maybe, maybe not.

If the valve’s not seated correctly it could get worse over time. (Unlikely)

If it the tyre’s not sealed against the rim correctly, one awkward pothole could debead it altogether. (Again, unlikely)

If it’s the previous repair, wouldn’t you want them to have done a proper job?

Well I'll take it to a different tyre place this weekend and see what they say ( as far as I know the valves have never been replaced and the car is from 2017 ).
Tyres are from 4 months ago.

It is most likely down to the plug as all the other tyres are fine, but again at 2PSI loss per month I doubt any tyre place would be willing to investigate.
I read that it's normal for tyres to lose a bit of air each month.
And going by the fact there's a plug in one of the tyres, I'd assume you can lose more air due to this.

Edited by MakaveliX on Thursday 23 February 18:17

[Pica-Pica]

I assume that before the tyre was plugged there was no significant leak.
In your situation, I would just accept that the slow leak was the price of a tyre plug, and just keep it pumped up regularly.
A couple of months ago, I had a half worn tyre, that had a screw in it. I chose to get a new tyre rather than a plug. My thinking was that punctures are so rare for me (probably 5 in 50 years of car ownership) I think that a new tyre is worth the cost.

[vikingaero]

Is it plugged or a proper BS standard repair? If It's plugged, then just replug it.

[Bainbridge]

I might get slated for saying this, but I reckon the leak is due to that tyre having now been fitted twice and therefore is not as airtight as the other 3.

[stevieturbo]

MakaveliX said:

Fair enough.
Do I need to be concerned about this or not ?

At such a small amount, not really.

Is the vehicle used much ? Does it sit about a lot ?

Tyres that lose pressure in small amounts, tend to do so more when not being driven. On my daily that doesn't really get used daily, one has a very slow reduction.

I just top it up every month or so. I've had the car around 16 months now and it's exactly the same. So no big deal.

If it was to get worse, or different maybe I'd look into it more. But I'll maybe need tyres in another few months, so can look further then.

[MakaveliX]

Heard a slight noise from the tyre area this morning ( from the tyre in question ) so investigated.
I put some water ontop of where the plug was and lo and behold there were bubbles.

Must have been very slow puncture as it was only about 1psi loss per week at the most. Bit the bullet and just got the tyre changed today.

[cuprabob]

MakaveliX said:

Heard a slight noise from the tyre area this morning ( from the tyre in question ) so investigated.
I put some water ontop of where the plug was and lo and behold there were bubbles.

Must have been very slow puncture as it was only about 1psi loss per week at the most. Bit the bullet and just got the tyre changed today.

With it being a new Michelin PS5 I would have tried another repair before replacing it. I would have still had the tyre repaired again and kept it as a spare.

Edited by cuprabob on Wednesday 22 March 15:37

[MakaveliX]

cuprabob said:

With it being a new Michelin PS5 I would have tried another repair before replacing it. I would have still had the tyre repaired again and kept it as a spare.

Edited by cuprabob on Wednesday 22 March 15:37

Here is the initial puncture from last year. It did go in at an angle rather than straight into the tyre. Maybe that had something to do with why the plug only partially helped ?

[E-bmw]

It could, the plug should have followed through the same hole.