Car tyre going flat at random intervals?

[DaveReading]

On 3 occasions over the last year or so, I've woken up to find that one of the tyres on my car (the same one each time) was completely flat, the same thing also happened once when I parked up to go for a 3-hour ride, it had deflated by the time I got back.

On each occasion, I've simply pumped it up again with my track pump and it has stayed rock-hard until the next time. I've changed the valve a couple of times as a precaution, but it happened again last night.

This time, as I was pumping away, I could hear a gentle hiss of escaping air. It wasn't from the valve, and I couldn't feel any obvious draught from anywhere on the tread or sidewall. Having got the tyre up to pressure, I rolled the car back a couple of feet and the hissing stopped. Several hours later, the tyre is still fully inflated.

Could this be a sign of damage or corrosion to the wheel rim, preventing the tyre bead seating properly? With the benefit of hindsight, I should have noted the orientation of the wheel when it previously deflated, but I didn't until today.

Has anyone else experienced similar?

MTIA

 

[Fnaar]

Having had a tyre pop at 70 mph on the motorway, (neither fun nor pleasant) I'd be replacing straight away.

 

[Globalti]

If you have alloy wheels, the wheel could be cracked. Dangerous at speed!

Take the wheel off this weekend, paint it all over with a strong solution of dishwash liquid and watch for bubbles.

 

[Arrowfoot]

Had the same problem last year as well. Had it checked at the garage and they said it was fine. Finally decided to replace it as I could not predict the next flat. Checked the internet and found out that the unexplained tyre deflation is a common occurrence.

 

[Drago]

Quite common on alloy rims. Assuming the wheel is undamaged and it not leaking from a crack etc then you can bodge it with Slime (available in a car sized doses) or else have a tyre fitter break the bead and refit it.

Also check if some Muppet has fitted weights to th edge of the rim. Alloys are supposed to use sticky weights as clamp on one's can cause air leaks.

 

[Buck]

On alloys you can get corrosion on the inner rim which makes an air tight seal difficult. Also if you have had a knock to the wheel/tyre i.e. pothole then the wheel can be fractionally out of true, again compromising the seal on the edge.

It could still be the valve as it may not leak sufficiently for you to hear it but it may not be air tight?

 

[tyred]

You will also find on old alloys that there is a build up of corrosion which allows air to escape slowly and I've also heard of alloys going porous.

 

[Levo-Lon]

Change the valve core..
my gsxr 1100 front used to go flat when over 120mph..weak valve spring

quite sacary slowing down to find the fron was flat..

 

[Yellow Saddle]

Change the valve core..
my gsxr 1100 front used to go flat when over 120mph..weak valve spring

quite sacary slowing down to find the fron was flat..

Hmmmm. At speed, the valve is forced closed by centrifugal force and the spring in effect becomes stronger.

 

[hedder2212]

Whip it off and spray some water over it to see if you can see bubbles anywhere.

Take it down to a tyre place, Have them remove the tyre and properly clean the wheel and have them refit the tyre properly. Chances are its just corrosion as mentioned, Sometimes it just happens and all it needs is a clean up with a wire brush. Have them change the valve at the same time and make them double check the valve inner is tightened properly at the same time (you can get a valve key for £4 or £5 also).

 

[vernon]

Hmmmm. At speed, the valve is forced closed by centrifugal force and the spring in effect becomes stronger.

I'm not convinced that you are right on this one. Draw us a diagram that contradicts this one.

 

[Levo-Lon]

Hmmmm. At speed, the valve is forced closed by centrifugal force and the spring in effect becomes stronger.

As per diagram..

 

[snorri]

Has anyone else experienced similar?

Yes. It turned out to be a poor puncture repair. When the vehicle was parked with the defective repair at the bottom of the wheel where the tyre tread and walls are distorted, then it leaked. When the wheel was off the vehicle and not bearing a load it would hold air indefinitely without losing pressure.
Check for a repair on the tyre and have it redone.

 

[Levo-Lon]

Yes. It turned out to be a poor puncture repair. When the vehicle was parked with the defective repair at the bottom of the wheel where the tyre tread and walls are distorted, then it leaked. When the wheel was off the vehicle and not bearing a load it would hold air indefinitely without losing pressure.
Check for a repair on the tyre and have it redone.

that may well be the reason..they dont do vulcanised repairs so much these days

 

[snorri]

that may well be the reason..they dont do vulcanised repairs so much these days

It could well be, I was recalling an incident from quite a few years ago.