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

[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.

[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?

[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 ?

[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

[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.

[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 ?

[MakaveliX]

So in theory should a plug completely stop the leak, or is it common for it to still leak somewhat ?

Just asking as each time I get a puncture I cannot keep buying ps5s.

Perhaps next time I get a puncture, ask the garage to double check with some water that the plug is not leaking after it is plugged

As I said . I think the fact the screw didn’t go in completely straight had an impact.

[MakaveliX]

ro250 said:

They'll love you asking that!

I've had 2 tyres plugged and both been completely normal afterwards. Sounds like you just got unlucky.

Lol yeah I thought it would be a valid point though seeing as I was driving round on a tyre with a leak for months when it was supposed to be sealed. Had it not been raining I wouldn’t have heard the hissing and most likely still driving on it.