Tubeless Sealant fails under pressure

I recently had a small puncture on the top of my Schwalbe pro 1 my tubeless setup. I am running stan’s sealant. The sealant filled the puncture, but whenever the wheel stops rotating and whenever I go to pump up the tires, the pressure (80psi) blows the seal. It seems to seal and not leak once it gets down to 20-30psi. Again this is a SMALL hole, so I’m confused about what the problem is. At first, I thought my sealant might be old so I put in new sealant but am having the same problem.

This is a problem with sealant and high pressures. Sometimes they seal and sometimes they don’t, I’ve got no idea why. A lot of the sealants are rated for high pressure but don’t always work as advertised.



Are you confident with your tire that you’ll descend without it puncturing? No? Then you’ll need to fix it, worse case replace the entire tire. Confidence in your bike is absolutely essential during road riding. I wouldnt ride my bike if I have an off feeling that something is wrong. Especially the wheels.

I always monitor my tubeless tires once a noticeable puncture has happened. If it doesn’t maintain pressure at 80 psi For a couple of days without any weight on it. theres a high chance there’s something wrong.

I’d plug it with a a dynaplug or any tubeless worm of your choice and reinflate the air.

As a precaution I’d top up additional sealant. Go more just in case. Personally I use 60ml of stans Race sealant.

It’s just much much easier to deal with tubeless punctures at home than on the road.

Hope it helps.

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I agree with this :point_up:

I’ve had a few of these sub-par seals and I’ve had joy fixing them by just cleaning out the sealant plug that has formed and let some fresh sealant have a crack at it.


This is the issues I had with high pressure and stans. It doesn’t have any small particles in it to help plug the hole. Finish line and squirt have been way better for me. In your case a dynaplug would work great for repairing during the ride.

I had a similar small hole on my gravel tire that wouldn’t seal. I now make sure to buy the small sized plugs and go straight for the plug if something doesn’t seal right away.

I saw this blog recently about using butcher string for very skinny holes:

The last time i used a Dynaplug i left it in there for another 1000 miles before deciding it was time to change the tyre. They work.


Try Specialized / Joe’s No Flats road pressure goo. It sucks for gravel pressures, but is better for road. For some reason, wet road tires seem to be the slowest to seal, which is when you get flats unfortunately.

Sealant also sucks for SLOW leaks. My buddy and I both have Conti gravel tires and both have a SLOW leak in the center tread. You could only find the leak in a bath tub of very still water. Tires full of goo, leak side down, overnight - still leaking. Leaned on one side, then the other, still leaking.

According to Stan’s, 40psi is the maximum pressure it will (Race version or standard version).

This has been extremely accurate in my experience and is why I don’t run Stan’s anymore…


Very accurate for me as well. I hadn’t seen that stated anywhere by stans, so thanks for that nugget. Squirt is similar to stans in that it is latex based, but it also comes with 2 different sized grains in it to help plug holes. I haven’t experienced a puncture yet that I know of since I started using it so can’t tell how well it plugs holes yet.

Possible the latex has dried out? There’s a lot of non-latex fluids in sealant that doesn’t plug holes and could give the impression you’re still covered. Topping up the sealant every few months at least is very necessary.

Besides that, I can’t recommend a plug-kit enough. I had a huge blowout some weeks ago and used the mtb-bacon on my 28mm road tires – worked perfect – that gash is like 1/4" or more and it’s been fine for the last several hundred miles. 2 days ago I got a tiny slow leak on the other tire. It was slowly seeping air and sealant, but a small road plug solved it immediately. My experience with them has been very confidence inspiring. I’ve stopped carrying a spare tube.

I’ve only had one puncture that I had to use more than one dynaplug. A big cut in the middle of the tire. Ended up using 3 dynaplugs to limp back to the car, it held for a few more days, but when I took the tire off to inspect it, I realized it was starting to separate.
I run 38c tires usually, so fairly low pressures. Some of my friends have had issues when the pressures are higher. I’m not totally sold on road tubeless, when it fails on a ride its a total PITA. I personally think its perfect for gravel and wider road tires. At lower pressures it really does work, often I don’t even realize it sealed a minor puncture until after I get home.

@cwiggum Thanks! I did put 60ml of new Stan’s in and it still blows under pressure. Do you think adding something to the stans (like glitter) would provide a particle base to help hold the seal under pressure?

If you patch it from the inside you will never know you had a leak there to begin with. Plugs are for emergencies but a patch can last the life of the tire without ever needing to think about it again. First I would try fresh sealant but if that fails then patch the tire and be done with it.


Patching instead of plugging also has the advantage that you can still stick a tube in if needed. If you have put dynaplugs or stans darts in, you have to remove them first, or you’ll puncture the tube.

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Folks - Stan’s says it right on the bottle - only up to 45psi. In my experience, it actually seals around 30 and doesn’t hold the seal at all above that. Race and normal, same problem in both. I had a hole in a set of Gravelkings so tiny that I couldn’t fit the tip of a seal pick in it and Stan’s couldn’t handle it.

So far, I’ve had better luck with sealing above 50psi with Orange Endurance and Specialized 2Bliss. Neither of them give a “max psi” and both claim they are good for road tubeless.

I used to use Stan’s across my bikes because it was the easiest to find, but it just doesn’t work for road - or even for the more narrow gravel. If you want to ride about 45psi, don’t use Stans (and in their defense, it is the same information you’ll find on their bottles).

It doesn’t say that on my bottle of Stan’s.

The only point where pressure is mentioned is under “Inflation”. It says: “Inflate tire to 30psi to seat bead. Do not exceed 40psi/2.75 bar. For road tubeless use, consult max pressure of tire and rim and do not inflate above the lowest listed pressure.”

That implies that you can use it over 40psi for road use.

I did have issues with small punctures in road use (smaller than a plug), but it usually seals eventually, and I run them at 60 psi. Maybe it slowly leaks back down to 40, and I just don’t notice.

I used regular Orange Seal on tubulars. They held out at 100+PSI just fine…

Another vote for Orange Seal. Stans works great on MTB with the lower pressures, but for road OS works much better.

Maybe I misread it, I’ll look again when I get back to the garage later