I've been puzzling for some time, why the rear tyres (tube-less) on our
tractor mower have been loosing pressure. I have taken them off a
couple of times to submerge them to find the leaks and found none. This
week I actually caught one in the act of deflating.

It seems if it happens to nudge anything alongside it, with the
sidewall of the tyre, it lifts the bead from the rim releasing enough
air to cause a leak which does not re-seal until they are blown back up
to their correct pressure.

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Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk