Retapw with 21mm tape. 25mm is too wide for his rim. First inflate with soapy present (dilute) and see if the tyre seat and does not unseat when you remove the valve core. Then inject sealant then reinflate.
Thanks. This was bang on in the end (took me a while to remember to buy some 21mm tape)
@user20714 started
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Retapw with 21mm tape. 25mm is too wide for his rim. First inflate with soapy present (dilute) and see if the tyre seat and does not unseat when you remove the valve core. Then inject sealant then reinflate.