F10 M5 weird loss of tyre pressure

[PaulM5]

Driving through heavy rain and six inches of standing water last night we suddenly had a tyre pressure warning come up. Put it down to the water interfering with the electronics and as we were very near our destination we just carried on for another hundred yards or so, parked up and went inside. Came out two hours later to find the offside rear tyre flat as a pancake. No sign of any damage. Got the pump out, re-inflated the tyre to 3 bar (a bit higher than usual) and drove home without a problem. Tyre has not lost pressure since then - still at 3 bar nearly 24 hours later.

Might not be relevant but should mention that car went for major service last week so they will have had the wheels off to look at the pads and the discs, I believe.

Anyone else had this happen to them?! Any idea what might have caused it? Very strange to suddenly lose all tyre pressure without any apparent cause.

[Joscal]

Sounds bizarre must be something wrong although can't see how it's anything to do with the recent work done.

Could it be a nail or screw that has resealed itself (if this makes sense!) having been re-inflated?

[Robb F]

I've had the same thing before, completely flat tyre, pumped it back up and it was fine after that.

No idea what caused it though.

[PaulM5]

Joscal said:

Sounds bizarre must be something wrong although can't see how it's anything to do with the recent work done.

Could it be a nail or screw that has resealed itself (if this makes sense!) having been re-inflated?

Yes, someone who works for me suggested that, I probably need to get the wheel off the car and take a really good look at it.

[PaulM5]

Robb F said:

I've had the same thing before, completely flat tyre, pumped it back up and it was fine after that.

No idea what caused it though.

Good to know I'm not alone! I'm wondering about the valve stem though, slightly faulty perhaps and the water somehow broke the seal. Or the valve itself. I'll probably get the valve changed as a precaution. That's if I can't find a nail or screw somewhere in the tyre. Never experienced anything like it in 34 years of driving.

[stain]

Check that the valve stem itself isn't loose.

[E-bmw]

Joscal said:

Could it be a nail or screw that has resealed itself (if this makes sense!) having been re-inflated?

Have had this before, what happens is:

With the nail on the 90% of the tyre that is not in contact with the road, it is sealed.

With the nail on the contact patch it distorts the tyre/nail enough to let air out.

You need to get it off & get it checked as it will happen again when you park it with the wheel positioned as above.

[PaulM5]

Mystery solved. Thanks to everyone who responded. Found the tyre flat again on Saturday morning and this time when I pumped it up again I could hear and feel air escaping from a huge cut almost in the middle of the tread. Inflated the tyre using the sealant system and then had new tyre fitted at Micheldever Tyres near where I live in Hampshire. So it seems as though initial damage was enough to allow all the air to escape at the time but then sealed itself up again. A few more miles were needed to worsen the damage so that the tyre could no longer hold any air. Definitely a new experience for me, didn't think it would be possible to have a puncture that would cause total loss of air but would then allow the tyre to hold air again.