Tyre Pressures

[Deskdiary]

A couple of weeks ago I checked my pressures and all 4 were only a PSI or two from the manufacturers recommendations so, of course, I increased them to the recommended amount.

A week ago the tyre pressure warning light came on, so I checked them again and one of them was down to 8 PSI (should be 32) so I inflated it, assumed I had a slow puncture, so was ready to replace it.

Since then it hasn’t deflated, and I check the pressure this morning and it’s still 32 PSI.

So, my question is, what would cause it to deflate so much given that, in the past week, it hasn’t deflated at all?

[DTCwordfan]

a stone in an uncapped nozzle - a slow leak from a tiny rupture that has closed up?

[douglas9401]

A local urchin who's not as bad as painted, leaving a little air in.

[shoota]

It is possible that when you checked the pressure and took the gauge away the valve stuck open momentarily allowing air out.

[Atheist]

Keep an eye on it. Sometimes things happen that we don't understand. like Brexit happening or Biden winning. I've got a similar issue with my French car and I check it when I've been away and if necessary phone my village mechanic to sort me out. If it carries on I'll probably get a new tyre, but if it seems under control I'll live with it while remaining vigilant. On the safe side, get a new tyre, I suppose.

[DTCwordfan]

or you leaked some off the tyre as you took the nozzle away, easily done.

[douglas9401]

Not to start a fight but, losing 24 psi when withdrawing the inflator?

Nae chance.

[shoota]

Swords or pistols?

[Hopkirk]

Perhaps the valve didn't reseat properly, (if that's possible).

[gulliver1]

I bet your tyre does not feel as deflated as Trump does.

[douglas9401]

Urchin, it's always urchins.

[Hymie]

It is possible that you have a defect in the tyre that due to the weight of the car, the static force on the rubber causes a split to open enough to leak air – this only noticeable when the tyre is stopped for a prolonged period in a particular position.

[Deskdiary]

That does make sense Hymie, as I’ve been going to work on my motorbike for the past week as the weather has been good, so I haven’t driven the car.

It needs to be monitored.

[douglas9401]

Mix up a weak solution of Fairy Liquid and water then apply to the offending corner. If there are bubbles, from anywhere, valve, tyre bead, tread, even the wheel welds then it's not urchins.

But I bet it is!

[AZardoz]

Damn straight, Douglas ☺ ... but I wasn't the culprit, honest.

[Hymie]

err, yes it does, the car may now be parked with the tyre in a position where the tyre split is not subject to force by the weight of the car (and so not leaking air). Looking at the tyre, you will see a slightly flat section at the bottom (due to the car’s mass).