i had a bit of a palaver last saturday, first time in nearly seven years of running tubeless, mainly due to my own mistakes.
so, the tyres were gravelking slicks, with over 5000km on them, rear tyre nearing its eol, front still looking v.good. i have topped up the sealant back in july before the alpi4000 and lejog and haven't added any since, so it has dried out. no big deal as i always carry some sealant with me, to add if needed in case of a puncture. on a wet and gritty ride, i had my rear tyre deflate and used the tubeless plug to plug a small hole (this was my first mistake - should have added the sealant instead). then after some time i felt that the tyre is getting soft again. rode a few km until it became flat, but also had a puncture on the front one at the same time. it was a busy road and a not good place to stop, so rolled 50-100m on flat tyres to a safe spot (second mistake - should've stopped straight away). added the sealant into the front tyre and started pumping, but the tyre has unseated from riding on the rims and the air was escaping quicker around the beads than my pump could inflate. the rear tyre has unseated too, so i was kinda stranded. not wanting to walk my bike to the nearest garage/bike shop i rode on flat tyres (for 3-4km) until a van driver noticed my misery, stopped and gave a lift to a nearest bike shop. i managed to seat and inflate the front tyre using their compressor. the sidewall of the rear tyre was chewed up from riding on the rim, so i bought an inner tube, inflated the tyre to 20psi and gently rode home. the rear rim needs fixing and there's some damage to the chain/seatstays from a floppy tyre rubbing against them, hey ho.
a few lessons from this:
although i hate the idea of inner tubes in tubeless tyres, perhaps it's worth carrying one (which i didn't do before)
stop riding asap, if the tyre deflates, to prevent it from unseating
carry a bit more sealant on longer rides, say 120ml
carry a co2 inflator on longer rides, in case the tyre unseats (very unlikely, but still)
be more diligent with the maintenance schedule, i loose the track with five sets of wheels on tubeless tyres
i have installed a gravelking ss tyre on the front wheel now, it has more rubber and better puncture protection (but is also a bit slower). the rear wheel will have its tyre hooks repaired and painted over and the wheel will be usable again.
with all my recent trouble, be in no doubt that tubeless is vastly superior system and i had close to 100,000k of trouble free riding in all those years. i have knowingly ridden with dried up sealant before for thousands of km, carrying 30-60ml of sealant in a saddle bag just in case - no punctures, no worries. it saved me from carrying inner tubes, tyre levers, inner tube patches, glue etc and saved a lot of time on the rides, not faffing about with flat tyres. i will change almost nothing and carry on enjoying the benefits.