How long can a pre-glued tubular keep?

i have a few used tubulars hanging around that still have glue residue on them. i was planning on taking one along for my first 1/2 im next week but was having doubts about whether or not it would actually stick to the rim if i did end up needing it. i put new tires on this past winter and they have been hanging in my basement (which is pretty dry) since then. if not, what can i do to prep one of these tires for emergency use (i.e. apply a thin layer of new glue and allow it to dry)?

as a follow up question, should i even bother taking a spare for the 1/2 im? thanks in advance for any advice.

I would take the spare. An 1/2 IM is long enough that your race isn’t over if you flat and you would be very annoyed if you needed it and didn’t have the spare on hand.

I don’t carry a spare at sprints but anything longer I do.

dt.