One tyre nitrogen inflated...

[C0ffin D0dger]

Think I know the answer to this but I thought I'd check with the masses.

Had a puncture whilst on holiday back in the summer and the garage that repaired it re-inflated the tyre with nitrogen, I didn't notice this until later on when I looked at the invoice.

Now the colder months are upon us it seems like the pressure fluctuation in my other three tyres is causing the flat tyre alarm to get set off on my BMW. When I check the pressures after this event three out of the four tyres are at a significantly lower pressure than the nitrogen filled one despite trying to equalise them a week or so back.

I'm guessing I'm okay to let most of the nitrogen out of the offending tyre and re-inflate with good old air. It's a run-flat so I assume I can let it completely down and refill (excepting the gas that's still in there as the structure of the tyre won't allow for complete deflation). The tyre place were okay about repairing it as it was never actually "run flat" as it was a screw through it causing it to go down slowly and apparently it is actually okay to repair these tyres under those circumstances.

Thanks.

[C0ffin D0dger]

55palfers said:

Interesting.

I pretty sure N2 and air expand / contract at the same rate.

Hadn't really thought about this but thought that was the whole point of filling a tyre with nitrogen. Google seems a bit vague, something about the nitrogen being dry, i.e. no moisture content unlike air, so this helps with temperature fluctuations, also any loss of pressure is slower as nitrogen molecules are bigger.

Maybe three of my four wheels / tyres have decided to leak?