Leaking tyre...or not?

[Patrick Bateman]

Back left tyre seemed to be losing pressure at about 2 PSI per day just recently, caught me by surprise when I checked it and it was 23PSI (after not checking them for a few weeks) while the other rear tyre was at the correct 35PSI.

Inflated it and checked the pressure a few hours later and it was fine. Drove 200 miles to Newcastle on the Friday and checked it before coming back up on the Sunday and it was down to 23PSI again. Rinse and repeat.

Now after having left the car untouched all this weekend I was expecting it to have deflated somewhat when I checked today but it was 35PSI as it should be.

Any idea what's going on? All I can think of is the valve was positioned towards the upper part of the tyre while I left it over the weekend just there- could it be that when the valve is positioned towards the lower part of the tyre that the weight of the car is managing to force air out through a dodgy valve? Can't think of what else would cause it.

[bigjobbo]

You may have parked on the puncture? Spray soapy water around the valve and the rim to check for leaks.

[Patrick Bateman]

I'll give it a go.

The tyres were stuck on fairly recently which is what made me think it could be a dodgy valve.

[STW2010]

I'm having this on both of my rear tyres. Both are fairly new and the deflation doesn't seem like a puncture in that the pressure drops over a week from 35 to 25, but then doesn't decrease much further. One of the reasons somebody suggested to me was that the alloys may have corroded around the rims causing an imperfect seal. Would seem like a good suggestion as the alloys are 11 years old, and are in need of a refurb.

[Eggman]

More likely that the tyre isn't making a good seal with the rim. If you've had it fitted recently, go back and tell the place that did it. They should be able to re-mount the tyre with some gloopy rubbery glue to make it seal.

[MGJohn]

Probably not! The tyre may be fine.

Any recently fitted tyres to alloy wheels using rim clip balance weights could be the problem here. Many fast-fit tyre outfits do not use self adhesive balance weights as they should and hammer rim clip ones on instead.

That often damages the unseen tyre-rim interface sufficiently to allow air to escape ~ as is the case here ~ note the number of air bubbles where I have sprayed with soapy water :~



This particularly bad example was on an inner rim face of the Alloy Wheel and probably like that unseen for years. The initial scratch through the protective paint coating of the alloy gets scratched the day the clip is hammered in place and road filth, damp and road salt attacks the unprotected metal immediately from thereon.



Over the years, I've lost count of the times I've had Alloy Wheels lose pressure because of uncaring tyre fitters. Whenever you have tyres fitted to your alloy wheels, insist that they use self adhesive weights and not rim clip ones.