H721
As far as I can recall from my days on the 747 (a long time ago ) the fusible plugs on the main wheels melted at 400 degrees Fahrenheit. I don't think the plugs had anything to do with pressure which is a separate issue. Those plugs always seemed to do their job OK but an inflated tyre on a hot wheel is certainly dangerous. However I've always felt that fusible plugs are not infallible which is the reason pilots are advised never to approach a hot wheel from the side. No such restrition on the steam locomotive as when those lead plugs let go the " red hot " steam went skywards.
Prince of Dzun.