…on the car.

Over a period of a few weeks one of the tyres (without fail) deflates to about 20psi from just over 30. Never goes much below 20 it would seem no matter how long I leave it. I keep pumping it up and it does the same. Car doesn’t get used much these days so haven’t been in a hurry to fix.

Now, aside from cries of auto neglect, can anyone surmise what the problem may be before I take it to the tyre place? eg. In case I am told I need a new tyre, where in fact it might be a faulty valve or something. Is that likely? TIA as always 🙂

porous rim ?

damaged bead seat ? (should be visible)

err, damaged tyre ? (I’m guessing you’ve checked it visually ?)

kids letting your tyre down, just a bit and repeatedly ? ( 😆 if it is)

Slow puncture? There will be a nail in it somewhere, perhaps.

kids letting your tyre down, just a bit and repeatedly ?

A kid with OCD and a tyre pressure gauge and nothing better to do ?

Is it on alloy? My wife’s car was doing this but going fully down. Nothing wrong with the tyre just got it re sealed at a local garage for 20 quid and it is fine now

A kid with OCD and a tyre pressure gauge and nothing better to do ?

deflates to about 20psi from just over 30

1)Consistentish length of pressing the valve down would do that just fine
2)Kids have nothing better to do: messing with a neighbour’s head? I’d have been up for it
3)You know how some suggestions aren’t entirely serious?, …

Are the tyres old? When they get old, they become brittle (you can see cracks appear between the tread) and they go down but once the pressure is low enough, they stop going down quite so quickly.

3)You know how some suggestions aren’t entirely serious?, …

Oh yes.

Probably a nail. The tyre pressure will drop to a point at which the air won’t force its way out.

Probably porous wheel. I’ve used Holts tyre sealant with good results to fix previous leaky Mini wheels.

A screw or nail will stay in the tread and the soft rubber inside the tyre will seal around it. Check the tyre carefully and hope the object isn’t in the shoulder of the tread, where it can’t be repaired because of the flexing.

I had stans sealant in one of the wheels on my old car for this reason, worked a charm. (I did check for damage and objects first!)

You could take the wheel off inflate it to say 40psi and then spray soapy water on it and see if you get any bubbles from leakage. Might be worth checking the valve using the same process too.

Turns out it was light corrosion on the rim and near the valve on the inside of the rim. All removed, cleaned up, re-balanced, £15.95. Pretty happy with that.