Plainsman

I could use some help from the crowd. Just had some warranty work done on a set of wheels, and put my tires back on. Hookless rims, and no compressor, so I took the cores out and pumped like mad until it felt like the tires seated. I was then able to re-install the cores and air them up. Hadn’t mounted them on my bike yet or put sealant in them, so they lost air in about a day.

Fast forward, I added sealant yesterday, mounted them on my bike, did the spin/shake thing, and inflated them. Checked today, and they still seem to be losing a decent amount of air. I thought they wouldn’t even take air if they weren’t seated. Am I missing something? 28c tires on Zipp 303s, about 2oz of sealant per tire.

WhyFi

I'm not quite clear on what's going on.

Are they being fully seated (showing the witness line all of the way around)?
Are the tires coming unseated at low/no pressure? Otherwise, I'm not understanding why you had to re-mount them, unless you're not adding sealant through the stem (which is, IMO, the easiest and cleanest way to go about it).
What tires are you using? You're aware that they need to be ETRTO TSS spec tires (for hookless/straight sidewalls)?

For the initial install, if the tires are fully seated, and you've got sealant in 'em, I'd at least let 'em spin for a good few minutes, if not go for a short ride. Some tires carcasses are more porous than others, and need to have that sealant really seep in.

cyclezen

for what I experienced... 'seating' a tire can take quite some pressure... I though 60 - 65 lbs (on 700c 38mm) would be enough... turned out I was wrong.
I had to get the pressure up to 85 almost 90 lbs to get the tire seated properly - left it that way for 20 min. and then brought the pressure down to running psi.
Rubber is 'sticky' and without some excess air pressure, the tire may seem as though the bead has 'seated' properly, but the rubber resists... the extra pressure assures the tire is properly against the sidewall.
28c would prolly take a bit more pressure to seat...
when I hand spin the tire, I do a real slow spin, and as tire rotates I move it from vertical to horizontal, back and forth, to both sides... sealant is viscous and takes a while to get around...
just my experience with 2 different wheelsets and tires...
Ride On
Yuri

WhyFi

This was generally my experience with other tubeless wheelsets and tires, but with the 303S (which is what the OP has), compatible tires, and wet/lubed beads, everything has seated with just a floor pump and without too much pressure (40-50 psi, maybe - max is 72.5); I think it's just the tolerances are much better (well, except for the Pro One Evo Addix - they seated easily but they also came unseated at very low pressure, which was made maintenance frustrating, at times),

terrymorse 

And here I used to think that mounting tubulars was too much of a hassle.

cyclezen

LOL! Sewups are a TOTAL PITA ! It's not just the mounting, which is a 'Rite of Passage' for many newbs, who end up getting Cement everywhere, on the tire, on the rim sidewall, on the clothes and certainly all over the hands. And then lining up the tire properly on the rim, to run straight, oooy ! I DID go thru that rite of passage, uuuugh...
Tubeless is certainly a bit more than butyl and clincher, But unless you have to remove the tire (which might not be as necessary for most small punctures...) The mounting is a one time - for a long time - process.
For road... I'm a little leery about 'tubeless' for MY road application. I really like tubeless for my mtb and also now my gravel - but both setups are able to run nice lower pressures - mid 20's in 2.4" for mtb and mid 30's (psi) for 42mm gravel. And both tire types are quite sturdy, so I don;t expect getting punctures or tire damage.
Now road is a different thing, I run 23 & 25 in higher performance tires, quite supple and thin, and at road pressures, which I keep quite low, the tire is still prone to more punctures from complete penetration... I would really loathe getting a puncture which didn;t 'seal' and then having to put in a tube, to make it back to start point.
I might consider using tubeless IF I was running 30 or 32 mm for road - but I don't...
I JUST put in some TPU into one Higher performance road wheelset... and going to take an inaugural ride today - to see how they feel....
I will report back - in the TPU thread... not here.
WhyFi also brought one thing , which I neglected to mention... lubing the bead when mounting/setting the tubeless tire. I'm on auto pilot for that. I've mounted SO many motorcycle tires that a good lube mix for setting the bead on a very stiff moto tire is absolutely needed - course we don;t use 'puncture sealer' when first mounting/using moto tires (at least no one I know uses sealer).
So I don;t know what my 'soapy' mix might do to the effectiveness of the 'Orange' sealer I use - so I use just plain water to 'lube' the bead.... not as good as my mix...
Ride On
Yuri

WhyFi

This is one of those things that looks way worse, and sounds like a much longer process, when written out. Last week, I had some waterlogged wheels (I got drenched on a ride and 40+ml of water made it in to the inner chamber of the rims), so I had to: drain the sealant, remove the tires, drain the water from the inner chamber, remount the tires, add sealant, re-inflate. It took about 12-15 min for both wheels, working at an unhurried pace.

oris

For the OP, what tire make/model are you trying to mount?

WhyFi and I both use the Zipp 303s and have good luck with most tires seating and holding with a track pump. I've personally only had issues with the Vittoria Corsa 2.0 TLR.

WhyFi

For years, Vittoria was mum on the Corsa 2.0 TLR lineup and hookless, but they recently came out and said, "nah - you shouldn't use them for that." They were on my list for a long time, but this makes me glad that I never got around to 'em.

In any event, just a couple of days ago, Vittoria released the Corsa N.EXT, which is hookless compatible in the 28mm-34mm sizes. I'll give those a try when the street price is palatable.

DaveSSS 

My 303s wheels with Pirelli p zero tires installed easily and seated with a floor pump. I use orange seal endurance sealant. Worked great when I got a double puncture from a 2 inch construction staple.

Canker

Take the wheels off and slather them up with soapy water and look for air bubbles. Most of the time when I have that issue it ends up being the valve stem has loosened up a bit.

eduskator

1) Make sure your tires are hookless compatible
2) Unmount the tires, clean your rim beads thoroughly (old sealant can be dried up / pasty), and mount them again.
3) Make sure you put enough sealant. I think 1oz is the recommended amount, but I always put 2.

Not sure why you remove your valve cores - I never do this. I don't need a compressor, a floor pump is OK. However, I know that some TL tires & rim combo are a PITA to mount properly. My former setup was like this. Getting new and better quality TL tires solved everything.

jaxgtr

Check to make sure your core is tight, I had one I thought was good, but found I need to give it another quarter turn. Once I did that, its been good.

bruce19

The only time (once in 3 yrs) I've had a problem with my Mavic USTs it was exactly this. Other than that they have performed flawlessly. I have them on 4 bikes.

ratell

The ideal for tubeless tires is to take them for a ride once you put them on. I find it really helps to fully seat them and evenly spread the sealant around.

If you are losing a lot of air my guess is there is a bit of the tire that isn't fully seated. Sometimes popping the bead and seating again gets them more solid.

Good Luck.

sshakari

I had a similar problem which the new valve core solved. Try soapy water and see where it bubbles even around the valve core.

Overdraft

This sounds exactly like my problem. I could easily get the beads to seat, I could pump them to whatever pressure I wanted with no obvious leaks but over any length of time, for example overnight, the rear would leak down to 40psi. I could go ahead and ride it at 40, it didn’t leak down any further even with my giant ass on board, but it wouldn’t hold any more than that.
Confusing AF. I tightened the crap out of the valves and cores and tried breaking the beads and rotating the tire to change the orientation on the rim, no dice.
Gave up and took it to the LBS where I bought the tires. According to them the issue was an imperfection they found on the wheel. The didn’t want to pfaff with my wheel so they tried fairing it in by putting on more layers of rim tape. That was the fix!
So to the OP, I’d try doubling or tripling the rim tape.

GBK233

Had a ***** of time with my first experience with tubeless. Problem was that I hadn't fully cleaned off all old dried up sealant from the beads...before I reinstalled the tires. Now....I love tubeless and won't go back. I do seat them with a pancake compressor. I don't want the hassle of pumping like hell...or buying a boost pump.