i did my tubles tyres with Joe’s no flats and it says on the bottle to re-apply the sealant between 3-12 months, well that was 3-12 months ago ( 😆 ) so what’s the score?

do i have to clean all the old stuff out 1st? or just top it up with new?

don’t have any of this faff with tubes!!! 🙄 😉

I’d just pop it off and have a look- the rate it goes off seems completely random tbh. As a rule, if the tyre sloshes it’s fine. If it doesn’t slosh it might also be fine. If it’s flat it’s probably not fine.

I clean out the old stuff where possible (though it’ll likely be glommed to the tyre pretty well) but that’s because I’m a weight weenie, normal people might not bother

I just take the valve core out and inject a new dose of sealant.

As above, every 3 months or the abouts

It allegedly breaks down into water and solid lumps eventually. I only ride 6 months per year in hot temperatures and my front tyre is fine for that period.

I get cuts in the rear tyre so need to reapply sealant there after repairs. Just empty the old stuff but don’t scrub or clean the tyre, as the stuff that’s stuck to it is what seals it. Put your new stuff in and you only need a quick shake to seal it all up.

Slosh test then stan’s syringe used as a funnel (take out plunger) to add more if needed.

Life’s too short to clean the old stuff out unless every gram matters (dried gunge weighs almost nothing, certainly less than the tread that’s worn off in the meantime)