A brand new tubeless tire is just as vulnerable to punctures as one that’s two days from retirement. It’s one of cycling’s many injustices. And nobody wants to throw away $80 (or more) just because of a slice that’s barely too wide for a traditional plug. Travis Engel happens to be in that very predicament. He has a nearly new tire with a terminal injury, and it’s been on ice waiting for science to find a cure. The Lezyne Tubeless Pro Plugs just might do the trick.

Before anyone says anything, yes, I know the auto industry has been using these things for decades. In fact, I wouldn’t be surprised if Lezyne’s new Tubeless Pro Plugs came out of the same factory as the (mostly) D.O.T. certified plugs you’d find at (mostly) reputable tire shops. I tried using one of those recently when I had an 8mm-wide gash in a brand new Maxxis Aggressor. And it almost worked. Bike tires are not like car tires. There’s much less structural support under the tread. The material around a slice always wants to pull itself apart as you add air pressure. It’s why bigger gashes need to be stitched, not plugged. Even with a very snug-fitting D.O.T. plug, my Maxxis Aggressor still had a troubling bulge and an incurable slow leak until I eventually gave up. But what if the damage isn’t quite that bad? If it’s too big for a couple bacon strips, but too small for major surgery?

I had just such an injury on my second day with a new Teravail Ehline. I managed to cram in enough plugs to finish the ride, but I never took it on the trail again. I’ll trust one or two plugs to hold on until a tire dies of old age, but I crammed five thick boys in this one, and it did not feel reliable. There was nothing but friction keeping that tangled wad of rubber from ripping out. But a couple weeks ago, the Lezyne Tubeless Pro Plugs arrived.

That D.O.T. car-tire plug kit I tried had 5mm, 7mm and 9mm plugs. Lezyne went much smaller, at 3mm, 3.5mm, and 4.5mm. A box includes two pieces of each. That’s probably about as big as you’d want to go, given the concept’s limitations. The hole in my Ehline was barely big enough to fit a 5mm allen wrench through, and yet it swallowed half of my emergency plugs. So, I pulled those out (with worrying ease), and started following directions … mostly.

Just like the old tube patch kits, you start by roughing up the surface. But I started fraying threads in the casing almost immediately, so I kept a light touch. Also just like the old patch kits, the rubber cement is meant to “dry” before bonding the two surfaces. I then peeled the sticker covers off the plug’s adhesive base and pulled it through until it bottomed out inside the tire. But I never got the inner base of the plug to make a satisfying seal. It was hard to keep the tire chassis and plug base from moving independently of one another. There was always a wrinkle somewhere. On a car tire, the surface is flatter, and professional installers use a knurled roller to really make sure the two surfaces are bonded. After some pressing and waiting, it seemed I was getting 360 degrees of adhesion, so I moved on, confident that tire sealant would make up for any gaps I might have left. I was less confident about what I did next…

This particular damage actually resulted from a pinch flat, so there was a second, smaller hole just above the bead. The golden rule of internal plug kits is that they are only for the tread. And Lezyne agreed, telling me this was not what the plug was meant for. But I tried anyway, pushing the 3mm plug through the hole. If it didn’t work, I could always start over and cram in some fresh bacon strips, so I went for it. I had to cut almost half of the base off, but again, my logic was that the sealant would probably do much of the work. Sorry, Lezyne. It’s all in the name of science.

I wanted to see how everything went before cutting off the excess, so I let them dangle as I added pressure. That ill-advised side plug had a slow, audible leak, but it stopped after I gave it one more tug. With no hissing detected, I sliced them both off, just a couple millimeters proud of flush, and went for a spin to swish some sealant. I checked on it a few hours later, and it wasn’t holding. The soapy water test confirmed that the problem was at the bead-level plug. So, I broke the bead, pulled it out, and sealed it back up with one doubled-over bacon strip. Maybe I could have forced the 3.5mm plug through and it’d have worked fine, but trial and error would be a bit of a pain. I think that’s the one shortcoming to this method. Not that it can’t heal sidewall or bead punctures. But that, unlike a traditional plug, you can’t add more if there’s still seepage. You need to be pretty confident that one plug will do the trick on your one puncture. And for the most part, that just means following the directions.

I’ve since gone on a couple pretty rowdy rides on this tire, and haven’t noticed any more pressure loss. But more importantly, I wasn’t even thinking about it. Again, I have complete trust in emergency plugs when used in moderation, but not in excess. What I like about the Tubeless Pro Plugs’ approach is not the adhesive or even the big flat rubber base. It’s that there’s at least something preventing the plug from getting pulled through from the outside. What seemed most important was that the diameter of the plug matched the diameter of the hole so the sealant had a fighting chance to plug it up.

With this experience under my belt, I’ll definitely be turning to the Tubeless Pro Plugs in a similar situation in the future. Any time I need more than one plug to fill a hole, I’ll swap to one of these when I get home. I’ll also be adding a couple to my bikepacking kit, since they don’t take up much space and can be a lot quicker and a little more reliable than a needle and thread in the right situation. Plus, it’s $14 for a set of six. Worth having if it can save an $80 tire.

Pros

• Save your tires and your money
• Relatively simple process
• Tried and true technology from auto and moto
• Designed to fit bigger holes than what standard plugs can fill
• Peace-of-mind that the plug will never pull out

Cons

• Requires removal of the tire to patch properly
• Hard to get a good seal on the tire sometimes
• Only intended for tire tread repairs, not sidewalls, yet with careful installation can be effective on sidewall tears too
• There is a limit to how big a cut it can repair

 

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