Your experiment was flawed, the tire is a sealed tire, there is no place for the liquid to evaporate away like with the paper towel thing you did. On top of that, a small pin hole prick would probably only leak out maybe a gram or two at the most, so you would have to have a lot of pin prick holes to lose 3 or so ounces of sealant, and no one gets that many holes. The sealant will dry out inside the tire, but what state does it leave when it dries out? sticky patches, and or dried CLUMPS of cured latex, the stuff is still in the tire, it just turned into another state.
This all got me thinking a bit and I looked up what I could find on the subject. I found an article on cleaning out the crud periodically. Their claim was that the water evaporated through the casing over time. I can imagine vapor slowly passing through the sidewall. Anyway I decided that since my tires on my MTB had numerous applications of sealant and zero cleanings I'd pop them off and check them out. So far I did just the front one.
It popped off the beads by hand and was super easy to un mount and remount. Other tires are undoubtedly much harder to mount and remove, but these (Stans Ravens on Stans wheels) are super easy. I put them back on with my hands and the beads popped on without removing the core before the compressor got above 20psi. Ithe air barely started flowing when they popped. I have even mounted them with a hand pump before.
Anyway I popped the tire off and weighed it it weighed 617g (1lb 5.8 oz) including what looked like an ounce or maybe two of liquid still in the tire. There was some sludge and small lumps. There was a coating of latex over the whole inside. there was thicker patches of jelly like more watery latex in places.
I scraped and scrubbed until it was bare over much of the inside with a very thin coat of latex over some of the inside.It is hard to judge the weight but a very small fraction of the weight of a latex tube. Any way the weight after all that was 536g (2.86oz.). Even if you add a very generous allowance for the coating I didn't get scraped off a 29"x 2.2" tube is likely to weigh more.
I tried to figure out how much sealant I had put in that tire and my best guess is 8 ounces so I figure that a fairly substantial portion of the weight does remain, but nowhere near all of it.
It does seem that if that is a worry an annual cleaning out may be prudent. Mine had been at six years since first install with no cleaning and some long spells just sitting while other bikes were ridden of I was doing other things. I would guess that is pretty much a worst case scenario for build up of gunk in the tire.
At the end of the day you have to do what you think is right for you, for me, I don't want to deal with trying to reseat a tire on the road because you can't so I have to carry a spare tube or two, I have to do that anyways whether it's tube or tubeless. And with using the right tires flats would not be all that common if at all. Of course, the argument would be that using the right tire you wouldn't get any flats in a tubeless either, and that's true! But if you do have one, it's more of a headache with a tubeless set up.
We all pick our poison. So far lately I have toured with tubes. I tour ultra light these days and have beem on skinny road tires. That has factored in and made me lean a bit more toward tubes especially since i don't own a road tubeless setup.
That said any tire I find pleasant enough that I choose it will get flats with some frequency. In some parts of the country they are quite frequent even with a tire with some moderate flat protection. Something like a gatorskin is about as far as I go toward flatproof. Raiding on something like a marathon plus is my idea of hell.
Another disadvantage that I forgot to mention is that the sealant is known for clogging valves.
Yeah, but I have not found it all that big of a deal. Just a minor annoyance.
I think the weight thing is false between the two types, by the time you add in sealant, special rim tape which is heavier than standard tape, you're pretty much a wash.
I tend to think that there is a bit of an advantage, but I am more interested in the supple ride that an effectively more flexible sidewall gives. that and the protection from thorn flats.
Running lower PSI using tubeless increases the chances of damaging the rim.
Running too low pressure with any setup does. Tubeless allows you to go a bit lower. You get to choose how low you go. The only thing is that with a tubed setup you get pinch flats when you go low.
[/quote]Removing a tubeless tire after the sealant has dried will leave you with a sailor's mouth, although if you use a C clamp you can break the seal easily enough.
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Broke both beads easily with my fingers. Zipped them off quickly and easily with one plastic park lever. Easily put them back on with my hands. I am almost 71 and have pretty bad arthritis in my hands and wrists (especially the thumbs). My point is that it likely varies pretty widely with the particulat tire, rim, rim strip combination. The even pop on the rime easy enough that I think I could do it with a mini pump. I wouldn't want to rely on having to do that and would always carry a tube.
Also my experience is with one particular setup and it is a 29er MTB at that. So it will likely not directly apply to a bike that I'd tour on. It may be closer to apply for folks who tour with fatter tired setups.
I wonder about whether the easy seating of the beads on my bike is in part because of the very light sidewall and whether someone who opts for a more robust sidewall would have a harder time. I'd have expected the opposite, but these tires pop right on every time i have tried them. Granted they have only been popped off the bead and mounted a few times (mounted when new, popped off to fix a broken spoke when trail debris got into wheel, popped off to check sealant level, popped off today, and maybe some other reason I am forgetting)
