Slowly deflating tyres

[LordAnthony]

Happy new year to all.
I had a flat tyre the other day after suffering from a slow puncture over a few weeks so I took a spare wheel (which had a cross-ply on it) and got a nice new 155 radial fitted.
I put the wheel on but a few days later the pressure has visibly reduced.

Any ideas what's happening here?

Could it be that the wheel has not made a proper sealed with the tyre?

Or is it more likely to be the antics of a delightful scamp (is "delightful scamp" the correct term?) letting air out (and then replacing the dust cap....).

[aupickup]

could be the seal around the valve, is the rim rusty around that area

[alanworland]

My tyres used to go down, had new ones fitted and when they came off the rims were not corroded but the paint was coming off and the air was escaping between the paint and the rim.
All loose paint was cleaned off all was then ok, but one has started to lose pressure (I suspect more paint is coming off)

[LordAnthony]

Thanks - I'll take a look

[bmcecosse]

Some wheels are rivetted together - could be leaking athe rivets, but most likely is rim leak - or valve leak. Lay the wheel flat and dribble soapy water into the rim well - between tyre and rim, also paint the soapy water around the valve stem - and wiggle the stem. You may need to fit a tube.

[LordAnthony]

My wife had a good idea - take the tyre back to the fitters and get them to check it.
Apparently it was a leaky valve as mentioned above so they wire brushed the wheel and stuck some sealer on and we'll see what happens.
Thanks to all.

[bmcecosse]

" Some sealer " - hmmm - wonder how long that will last! Make sure you have a seviceable spare - and the means to change it!

[Fozz]

I have the same problem, all my tyres slowly deflate and I have to pump them up before each trip!
My wheels are not in bad condition so I suppose it may well be loose paint on the rims. It's worse now the weather is cold, and the tyres are less flexible. They go down to about 20psi apart from one front one which has gone down to nearly 10. As I am very short of money atm and my MOT is next month I will have to put up with it for now, just glad to know the probable cause.

[bmcecosse]

Test around the edges - and at the valve - with soapy water and a small paint brush to find the leaks!

[LordAnthony]

All still appears to be ok for me so far since the wire brushing and sealer.

[Fozz]

This is probably an extremely stupid question, but you do have to take the wheels off and lay them flat to check for leaks with soapy water?

[bmcecosse]

I don't suppose you HAVE to - but it's likely to be more effective!

[autolycus]

Or park in a very deep, soapy puddle.

Tyres don't drop to a particular pressure and stay at it: they carry on dropping. If you ever find a tyre at 10psi something is seriously wrong - either you're checking them too rarely, or there's a very bad leak. I'd say it was essential to find out where it's leaking, and don't stop looking when you've found the first leak, as there could be several. Round the tyre bead (inside and outside), round the valve (push it in all directions while you watch), the valve core itself (the spit test), and, most importantly, round the whole of the tread, looking for embedded objects like screws. The reason for checking for embedded objects is that they can often seal quite well (if it's a tubeless tyre) for a while, but the continuing flexing of the tread can eventually let it escape, and with it the rest of the air in the tyre. And then you could be in the sort of trouble that makes being short of a few quid to get them checked seem pretty trivial.

Should you really be running a car at all if you haven't got the money to keep it safe?

Kevin

[Fozz]

I have looked for embedded objects and can't see any.
She will have to go in to garage soon to get windscreen washer sorted prior to MOT so will ask to have the tyres checked out. I check them every few days, and always pump them up before I go out. I suppose because they go down very slowly and were brand new tyres when I bought the car I didn't worry as much as I should have.