Puncture plugging powers
We put nine mountain bike tubeless sealants through the slash test to rate their puncture-plugging powers. Just what is the best tyre sealant out there?
Converting to tubeless is one of the best upgrades you can do to your bike and since most modern rims and tyres are ‘tubeless ready’ you have everything you need to cross over. In fact, the only things you’ll have to buy are a couple of tubeless valves and a bottle of sealant.
As the name suggests, tyre sealant seals punctures but in a tubeless system it also has another function – it coats the inside of the tyre, creating a barrier against air loss. The is because tubeless ready tyres are not fully air tight and eventually leak air through the casing. Some of the first UST tubeless tyres were better at retaining air but they were heavy and expensive and it doesn’t make sense to have them on your bike if you’re not intending to switch. This is why bike manufacturers fit lighter and cheaper tubeless ready tyres and leave the conversion up to you.
Tyre sealant is the life blood of a properly function tubeless system, which is why it’s important to buy one that really works. They are loads of formulations available, with unique and often secret additives to help seal punctures and there’s also a wide range of prices. We have nine on test – all put through the ringer to find that one sweet blend.
Tyre sealant particulate
The best sealants contain particulate, which helps clogs the hole when you get a puncture. A variety of sizes works best but only the larger particles are visible.
Tyre sealant viscosity
Sealant is basically a glue (a bit like Copydex) so will eventually dry out. To keep it liquid ensure there’s always a pool of reservoir in the bottom of the tyre and top it up regularly.
How we tested
Bottles of sealant come in lots of different sizes but it’d be nice to know the ‘price per tyre’ figure, which is why we’ve calculated this for you. It’s based on the size of the container that will fill two 29×2.4inch tyres, meaning 240ml or bigger. Despite some sealant manufactures recommending more or less, we’ve settled on 120ml per tyre because this adequately coats the inside to limit air loss but there’s still enough left over to form a pool at the bottom for clogging holes. Obviously, this price per tyre will change if you buy a bigger/smaller container or you run thinner or smaller 26inch tyres because the recommended amount of sealant required for those is less.
Sealant has an operating temperature and we wanted to put this to the test, so we put all of the sealants in a freezer set to -18c and an oven at 50c to see what would happened. It doesn’t fully replicate real world conditions but it did give us an idea how the sealants would behave in warmer or colder climates.
By its nature, sealant will eventually go off in your tyres – it either creates a skin or forms into ‘tyre pearls’, tiny balls that roll around inside. It’s impossible to calculate how long sealant stays liquid because it’s effected by use, temperature, volume and the make-up of the sealant itself. Manufacturers recommend anything from two weeks to four months. Our advice is to check it regularly and top it up as necessary.
To test the sealants ability to heal punctures we filled a 29×2.4in tyre with 120ml of each of the sealants and then pierced it with a 2.75mm bradawl, a 5mm screwdriver and cut the sidewall with a 6mm scalpel. Admittedly punctures don’t always go in and out, for example if you ride over a thorn it can just stay stuck in your tyre, so sealant only has to seal round it. Also, sidewall cuts are often way bigger than 6mm or a jagged shape, but then very few manufactures say their sealant will plug tears bigger than this anyway. For us plugging the two holes was a minimum, sealing the tear was a bonus.
Mountain bike tyre sealant reviews
Bontrager TLR tyre sealant
Price: £24.99 (Size tested 950ml)
SPECIFICATION: Price per tyre £4.99 • Sizes: 59ml and 950ml• Contact: trekbikes.co.uk
Bontrager ammonia-free TLR sealant is available in two sizes – a 59ml one shot and a workshop-sized 950ml bottle. At just under £5 per tyre the bigger size is better value, but Bontrager says you don’t actually need this much. It recommends 59ml for a 29er tyre and if you use the big bottle that works out at £1.55 per tyre, the small bottle £3.75 per tyre. We did put Bontrager’s claim to the test and, while it coated the inside evenly, there wasn’t much of a pool at the bottom of the tyre for sealing. This stuff is quite thin, with smaller particulate to help clog the holes, so we definitely err on the side of caution and go with more.
Bontrager also claims TLR sealant will heal punctures up to 6.5mm in diameter and while it plugged the leak when we poked in the 2.75mm skewer into the tyre, it oozed constantly from the larger 5mm hole.
TLR sealant remained pretty neutral, is easy to clean up and would easily deal with thorn-sized puncture but it struggles with anything bigger.
MBR rating: 6/10
Continental RevoSealant tyre sealant
Price: £12.95 (240ml)
SPECIFICATION: Price per tyre £6.47 • Sizes: 240ml and 1lt • Contact: conti-tyres.co.uk
A 240ml bottle of RevoSealant provides enough sealant for two full-size 29er mountain bike tyres but at nearly £6.50 a tyre it’s the third most expensive on test. If you buy the 1litre bottle the price drops to £4.55 per tyre but the consistency and make up don’t seem a lot different to sealants costing a couple of pound less. Continental says it’s water based and doesn’t contain ammonia, which apparently harm rubber and bare aluminium but it’s pretty thin. It coated the inside of the casing thoroughly and there’s a pool left over in the bottom of the tyre for sealing but there are no obvious signs of any small particles to help clog holes.
Once we removed the bradawl from the tread it took quite a few spins to seal the 2.7mm hole and when we pushed the larger screwdriver through the cased it never really sealed that properly either. With it struggling so much the sidewall tear was just a milky mess.
RevoSealant didn’t alter consistency in the freezer or when we warmed it slightly and it’s dead is easy to handle but the limited sealing and price really count against it.
MBR rating: 5/10
Effetto Caffelatex tyre sealant
Price: £20 (2lt)
SPECIFICATION: Price per tyre £4.80 • Sizes: 60, 250ml and 1, 10L • Contact: upgradebikes.co.uk
It’s well known that Effetto has a slightly different take on sealant. Its Caffelatex is incredibly thin, so provides really good internal coverage to limit air loss but contains something called Actifoam, so once you puncture the tyre it bubbles up, forming a sort of froth on the tyre surface. This is exactly what happened with all three of our test punctures, but Caffelatex only blocked the smaller 2.75mm hole permanently. The larger 5mm hole broke open when we applied weight or added air, and the sidewall cut just leaked constantly.
Caffelatex is good value and doesn’t smell like an old sewer but it just seems incredibly thin compared to every other sealants on test.
To make it more effective we’d like to try Effetto new particulate additive Vitamina CL. It’s only just been launched but you add this directly to the tyre to increases the maximum repairable puncture size from a claim 6mm to a whopping 8m. You can buy a 200ml pot (enough for 2litres of sealant) for £20 but the obvious question is why doesn’t it come added as standard?
MBR rating: 6/10
E13 Tire Plasma tyre sealant
Price: £4.50 (120ml)
SPECIFICATION: Price per tyre £2.39 • Sizes: 120ml and 1L • Contact: silverfish-uk.com
Tire Plasma is sold in an easy-to-use 120ml sachet (shown) or a 1litre bottle. The price per tyre is calculated from the latter, making this the best value sealant on test.
It’s made using acrylic resin, which is none-toxic, cleans up with water, and doesn’t feel all chemically or sticky. It contains quite large particulate to help clogging but E13 does say it will only seal holes up to 4mm in diameter.
Of all the sealants that we put through our basic temperature tests, Tire Plasma was the most reactive – lumps of ice had formed after an hour in the freezer and it thickened considerably when heated.
It sealed the smaller 2.75mm hole after barely one revolution and even when pressurised the tyre this repair held fast. It didn’t seal the larger 5mm puncture though and, when we slashed the sidewall, it just sprayed everywhere although to be fair, E13 does say it wouldn’t seal anything this big.
For plugging holes Tire Plasma is limited to smaller tears but it’s great value and dead easy to work with.
MBR rating: 6/10
Hutchinson Protect’Air Max tyre sealant
Price: £79.95 (5litre)
SPECIFICATION: Price per tyre £2.87 • Sizes: 120ml, 1L and 5L • Contact: windwave.co.uk
When we called Hutchinson it was out of stock of the smaller sizes of its Protect’Air Max so sent this whopping 5litre jerry instead. If you buy this size, filling a single tyre costs £1.91 but it is a big investment. The more useable sizes are the 120ml and 1litre, but the small bottle will only fill one tyre so the best value option is the 1litre, you get about eight refills at £2.87 a wheel.
Protect’Air Max is very thin so disperses easily in the tyre. It also remained unaffected by our temperature tests and a did an okay job sealing the smaller hole with barely one revolution of the tyre. However, the larger one took a little bit more work –alternating between spinning the tyre and positioning the hole at the bottom and then leaving the resulting plug to partial dry out.
In its current from Protect’Air Max wouldn’t seal anything bigger than larger thorns but mix it with some thicker sealant or add a bit of home-made particulate and you could really milk the incredibly low price.
MBR rating: 6/10
Muc-Off No Puncture Hassle tyre sealant
Price: £9.99 (140ml)
SPECIFICATION: Price per tyre £8.56 • Sizes:140ml, 1L and 5L • Contact: silverfish-uk.com
Muc Off’s oddly named No Puncture Hassle sealant is brand new and, regardless of the size you buy, is one of the most expensive sealants out there. We tested the 140ml sachet, which easily filled our 29×2.4in test tyre but it has a thin nozzle that fits directly in a Presta valve stem reducing mess and waste.
Despite being one of the thickest sealants on test, NPH distributes evenly around the inside of the tyre. When we first squirted the full 140ml there’s didn’t seem like much left in the bottom of the tyre but we needn’t have worried because this luminous pink gunk sealed the 2.75mm puncture in barely a revolution. It also sealed the larger 5mm almost instantly and, while most sealants on test only sealed the sidewall cut temporarily, NPH sealed it permanently and we even manged to re-inflate the tyre after about an hour.
Muc Off No Puncture Hassle isn’t cheap but it works, and in our book that makes it a top buy. If you want the best out there, this is currently it.
MBR rating: 10/10
Orange Seal Endurance tyre sealant
Price: £7.99 (118ml)
SPECIFICATION: Price per tyre £7 • Sizes: 118ml, 236ml, 473ml, 946ml • Contact: extrauk.co.uk
Orange Seal claims its Endurance sealant can last up to a 120days before it dries out, which is about four times as long as its regular stuff and you only pay an extra £1 across all the sizes for this increased durability. At £7 per wheel, only Muc Off’s sealant is more expensive but Orange Seal Endurance remained totally fluid in cold temperatures and easily sealed the 2.75mm and 5mm holes in our test tyre. The company claims it will seal slits up to 19mm and, while it did plug our 8mm cut, it was only temporary, when we added a bit of weight the tyre split open again. Like a lot of sealants, we reckon you’re just going to have to work it into the cut repeatedly and let it partially dry out if you’re trying to get going out on the trail.
We’ve haven’t noticed Orange Seal lasting significantly longer than most but it does form into a protective skin on the inside of the casing, which is really effective at sealing small and medium sized punctures.
MBR rating: 9/10
Stans NoTubes tyre sealant
Price: £4 (59ml)
SPECIFICATION: Price per tyre £4.57 • Sizes: 59ml, 473ml, 946ml • Contact: paligap.cc
Stans NoTubes regaulr sealant is available in this handy sized 4oz (59ml) bottle but to fill a 29inch mountain bike tyre you’d need at least two bottles and it’d work out quite expensive at £8.13 a tyre. If you buy the pint bottle for £18 it suddenly haves in price to £4.57 per tyre.
NoTubes is latex based and has a wide operating temperature, so remained unaffected during our cold and heat tests. It is quite thin, so a little goes a long way and coats the inside of the tyre pretty well to limit air loss.
To aid sealing NoTubes, contains tiny crystals, which the company claims help plug holes up to 6.5mm. It sealed both the 2.75mm and 5mm holes after one revolution but the latter broke open when we put any weight on the tyre. It did eventually heal but only after bathing the hole several times with the excess sealant and rotating the tyre about a dozen times.
NoTubes standard sealant is good value and works reasonable well but we’ve had better success with the company’s Race Sealant, it contains extra-large crystals and plugs bigger holes.
MBR rating: 7/10
Vittoria Pit Stop TNT EVO tyre sealant
Price: £22.99 (500ml)
SPECIFICATION: Price per tyre £5.52 • Sizes: 200, 500, 1L • Contact: zyrofisher.co.uk
We’d like to be able to tell you there’s a difference between Vittoria standard Pit Stop TNT sealant and the Evo version shown but details have been really hard to come by. In fact we’ve had both and they seem identical, so we reckon it’s just the way they’re named.
Pit Stop TNT EVO is a thin sealant and it retained this viscosity when chilled, however we noticed a skin had formed over the sealant when it was heated. In our torture chamber the Pit Stop TNT EVO sealed the 2.75mm puncture after barely one revolution and did the same for the 5mm hole initially but it eventually when we put weight on the tyre. It didn’t seal the sidewall cut either we played around with positioning the slash rotating it to the bottom where it could submerge in sealant but it didn’t help.
Pit Stop TNT EVO plugs holes quickly but lacks the larger particulate to seal bigger cuts and sidewall tears. You could easily add some home-made additive to boost its clogging power but there are cheaper alternatives where you could do the exact same thing.
MBR rating: 7/10
Conclusion: the best tyre sealant
What’s surprised us most about this test was the actual cost of the different sealants. Converting to tubeless is a totally no brainer because there are some really obvious advantages but when you look at how much it actually costs to fill two tyres and then re-charge them over the course of a year, sealant is actually pretty expensive. If there’s a hot summer or heat wave, which is what we’re having right now, then you may need to renew the sealant in as little as two weeks, we’ve tested some sealants that really do go off this quick. Even if we’re generous and you only have to top up your sealant, say every three months, that’s still four times a year, and based on our costs per tyre prices can be anything from £22.96 to £68.48! When you consider inner tubes are as little as £2.50 on-line are you really going to get through 27 tubes in the same amount of time? We’re not suggesting you go convert back to tubes but if you’re constantly swapping tyres or ride in hot weather, a big tub of sealant is a must buy because you’re going to get through it.
One of the corner stones of this test was the ability of the sealants to do what they say on the tin and that’s to seal a puncture. Every sealant we tested plugged the smaller 2.75mm hole but when it came to the 5mm puncture, some didn’t work and with others we had to wait quite a while for it to congeal and plug the hole. Very few sealed the 6mm sidewall cut, which surprised us because 6mm isn’t that big, you’re only looking the thickness of a pencil.
It’s not all bad news though, some sealants did a great job. Stans NoTubes Standard sealant is good value and readily available in a lot of bike shops, and while it can be hit and miss on the biggest holes, it’s definitely worth paying the extra £1for the Race sealant, which is a lot more effective.
The top two sealants in this test are the most expensive but they sealed both hole sizes and did a good job at sealing the cut in the tyre sidewall, so that you could actually ride home rather than having to repair the tyre or fit a tube. We found you do need a bit more of the Orange Seal Endurance than claimed but it creates a nice layer on the inside of the tyre and the dipstick for measure the sealant level is a nice touch.
Muc-Off No Puncture Hassle will cost you over £17 to do two standard sized tyres, more if you run Plus tyres, but it works. It’s a little bit thicker than most but it spreads out evenly in the tyre and sealed all the holes and cuts. It’s better value in the larger one litre size but the small 140ml pouch is convenient and even comes with a scoop, a valve core remover and a UV detector, which is a little light that you shine on the tyre to spot tiny leaks. If you’re running thinner tyres, compete in XC or Enduro events or just ride in a place where there’s lots of thorns, Muc-Off No Puncture Hassle is the one we’d recommend.