Should a tubeless tire be able to hold air without sealant?

[fignon's barber]

Today I was changing my shamal carbons over to gravel mode with Pirelli Cinturato H tubeless tires. I've always resisted the tubeless craze, but decided to try. Before committing, I wanted to try without sealant. They went on easily, and snapped in with a floor pump. Should they be able to hold air overnight?

[AngryScientist]

They might, but probably not. It's not the tires that wont hold air, it's everything else. I believe the carbon shamals are a solid rim bed with no holes? If that's the case, you might have a shot, but in general tubeless set-ups do require sealant to ride.

[Dave]

A lot of the sealant on my tubeless setups goes into sealing around the bead. That indicates some amount of bead stretch that creates small leaks to be filled. The best reason to use tubeless is to have the sealant seal small punctures that would cause a flat with a tubed tire.

I also prefer rims that require no rim tape.

[Likes2ridefar]

I have some that will inflate and hold air but it leaks out fast. I probably wouldn’t expect it to hold overnight.

I just inflated two Vittoria barzo 650b 2.1 xc tires dry.

[prototoast]

In my experience, some tubeless tires hold air indefinitely without sealant (Mavic and Hutchinson tires come to mind).

Others might hold air for a few hours or overnight, but not much longer (Specialized, Schwalbe).

And others don't hold air at all without sealant (Panaracer, Vittoria).

[Jaybee]

I used to consider a tubeless tire ready to ride when it would hold air for 4-6 hours without sealant. If it deflated, I would retape. That's too stringent and I wasted a lot of expensive tape. I now tape, inflate, make sure the bead pops and looks good all the way around and I can't hear any huge leaks, then I add sealant and inflate. Hasn't failed me yet.

[christian]

I have the 700c X 44mm version of those tires on my commuter. In my case, they don't seal well or keep inflated longer than 12 hours without -any- sealant. Once seated with sealant, they seem to hold their own, even once the sealant dries out.

[Mark McM]

A true Tubeless tire will hold air without the need for sealant. However, most tires called "tubeless" are actually Tubeless Ready (often abbreviated TLR), and these tires require sealant. There have been a few Tubeless tires, such as the Mavic UST tires, but most are Tubeless Ready. A new Tubeless tire which doesn't require sealant has just been announced by Hutchinson:

https://www.cyclingnews.com/news/hut...lant-obsolete/

(Note: If I recall correctly, Mavic's UST tires were also made by Hutchinson.)


(Technical note: One of the main differences between Tubeless and Tubeless Ready tires is that Tubeless tires have an air impermeable layer bonded to the inside of the tire casing, usually made of butyl rubber. This adds weight and rolling resistance, which is a large part of the reason that true Tubeless tires have not been popular for performance tires.)

[AngryScientist]

Originally Posted by Mark McM

A true Tubeless tire will hold air without the need for sealant. However, most tires called "tubeless" are actually Tubeless Ready (often abbreviated TLR), and these tires require sealant. There have been a few Tubeless tires, such as the Mavic UST tires, but most are Tubeless Ready. A new Tubeless tire which doesn't require sealant has just been announced by Hutchinson:

https://www.cyclingnews.com/news/hut...lant-obsolete/

Hutchinson describes its latest Challenger Tubeless road bike tyre as an all-season ultra-endurance and training tyre and claims that its new tech provides a lifespan of up to 10,000km,

I predict this road tire will ride about as good as a garden hose in subzero temperatures.

[Likes2ridefar]

If it isn’t a garden hose it is appealing. Otherwise I,m having a tough time seeing why you wouldn’t just use a more durable regular tire and tube.

I would expect a tire like that will puncture eventually and where I am sooner rather than later most likely.

[joralieu]

I ran Hutchison tubeless tires on alloy Shamal's without sealant for a few years. They held air fine. They were really tight and hard to remove though.. I went back to tubes.

[fignon's barber]

Originally Posted by AngryScientist

They might, but probably not. It's not the tires that wont hold air, it's everything else. I believe the carbon shamals are a solid rim bed with no holes? If that's the case, you might have a shot, but in general tubeless set-ups do require sealant to ride.

OK, so I tested them. No tape, just mounted and did a 15 minute test run. Left them overnight. Maintained about 75% of the air. I liked the light feel of them without tubes. The main purpose of this was to see if it would be worth the hassle of sealant. Based on the feel, I think I like tubeless and will set up with sealant.

[Veloo]

I've wondered too if they will work sans sealant.
If you have to pump up again every 24 or 48 hours, is that really that far off from latex tubes?

[saab2000]

I have some DT-Swiss gravel wheels and they definitely inflated and held air overnight without sealant. Not indefinitely but the fit of the tire to the rim was snug enough that it worked well. Inflated with a floor pump.

A buddy of mine tried this with road tires but learned that going without sealant for the long term wasn’t viable. He kept having deflation, sometimes complete deflation, of the tires.

[cgates66]

I don't ride mountain very often - but I do have an old mountain bike, with Mavic I think 819? UST rims and tubeless I think 2.2" Maxxis tires. I have not changed or added to the sealant since ca. 2008. I should say here that this is not a good practice, I don't recommend it or rely on it, but rather just as a data point.

If inflated to a fairly rigid 55 PSI, they'll hold air for at least a couple of hours and remain rideable, and I'm guessing the "sealant" or what's left of it is doing precisely nothing there given the age. I don't know about big hits.

That's on a fully suspended mountain bike though - on the road, I'd go for sealant and change it "on schedule".