I got my first set of brand new tubeless wheels (Mavic Aksium Elite UST) and next day I had a somewhat large (it looks more than 4 mm) puncture. The sealant did its job, but my teammates described it as a "beer flowing from my tire".

Now I'm worried that I might need to add more sealant to the tire, but I don't know how much and I don't want to waste whatever fluid remains inside, since it is totally new. Any recommendations?

Also, is it OK to leave the tire with such a puncture as it is now?


3 Answers 3


Pull the valve core and poke a 2mm Allen wrench down to test the fluid level with the valve at the 6 o'clock position with the tire off the ground. You want "some" free liquid. How much depends on the tire size but I usually look for at least 3mm.

Some amount of sealant from a new installation goes to coating the tire and in many cases filling in the porosity of the casing. So if you find there's no free sealant and you're surprised you lost that much, that might be why.

How much free sealant you want is largely based on preference in terms of flat resistance versus weight. It's not a super exact science.

With the valve core removed you can inject more sealant using a commercial injector or various improvised tools.

  • 2
    The OP mentioned a concern about not wasting remaining sealant. May be worth mentioning that you top up through the opened stem, so the original sealant is kept. No need to remove the tire.
    – Rider_X
    Commented Feb 13, 2020 at 2:17

Depends on your confidence levels - if you're going for a 3 hour tour then its a very long walk home. For a 5 minute roll to the local shops, a walk would merely be annoying.

Topping up sealant is normal, and should be done every ~6 months anyway. As long as you have the same stuff, I'd consider it. First try to ascertain how much is left in the tyre, perhaps by shaking, or unseat the tyre from the rim and have a look at the bottom.

A puncture "repaired" by sealant should be permanent - but don't try to knock the "tree" off the inside unless you're fitting the emergency tube for other reasons.

However I'd always carry a tube and a pump and levers, in case the sealant doesn't work, like a gash in the tyre.

  • I've had a puncture 'repaired' but only up to a certain pressure, anything over that and away it went again. Commented Feb 13, 2020 at 10:02
  • @LamarLatrell yeah in my experience, road tyres at high PSI are a lot more stress on any puncture repair, whether it be sealant, a sticker, or a proper vulcanised patch. MTBs at 30 PSI are a lot more forgiving.
    – Criggie
    Commented Feb 13, 2020 at 10:10
  • 1
    That's true, I had a friend swear by Lezyne glueless patches, so I tired them. I stopped at the lights once in Melbourne 2 years ago in 40deg heat, the patched area (randomly) rested on the road for about 20s before the cement melted. The 23mm 700c tyre was flat from 100psi in about 2s. My friend rides at round 30 something psi... :) Commented Feb 13, 2020 at 10:14
  • @LamarLatrell Stickers are great for last-line puncture fixes, once you ran through all your spare tubes. And they're wheel-size-agnostic so you can give them to other stranded people who would otherwise be walking. But not as primary.
    – Criggie
    Commented Feb 13, 2020 at 19:04

I know it's not a permanent solution, but you can actually use bacon strips, then put more sealant inside the tire. It works better this way because the bacon strips absorb the sealant. BTW bacon straps are a mountain bikers thing, but i've seen them work on road bike before too. I hope this helps!!


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