Tubeless tire help please. Soft rear tire. Panaracer gravel king slick 700x35mm

Had this tire on my bike since just before the Alzheimer’s Big Bike ride in Fall 2023. Probably 2000km on it.

Got a flat on LTGR #4, and havent been able to get it to stay inflated since. Will usually be noticeably soft (like under 20 psi) after about 10km. Seems to hold about 10-15psi for a few days.

Things I’ve tried.

  • I dismounted the tire, and added new sealant (about 2.5oz of stans sealant). It was a 40 minute pain to get it to seat (this is with a 25 gallon twin cylinder compressor). I finally got it to seat. I think I got the technique down now.

  • When I had the tire dismounted, I noticed that the tag end of the tape was lifting a bit. Unfortunately I did not have tape to replace it.

  • been on 2 bike rides since, and the tire needs air after about 10km. I am getting very familiar with my mini pump.

  • I googled the internal width of my Giant PX2 rim and it is 19mm, so i ordered some 23mm tape to retape it. Should be here tomorrow.

  • this afternoon, I took the tire off and dumped out the sealant and sprayed it and the rim off with the hose. The internal width is indeed 19mm. I got the old rim tape off, but some of the adhesive from the tape is stuck to the rim. I tried goo gone and a rag, and Isopropyl Alcohol 70% to get rid of the adhesive. I also tried a rubber adhesive removing wheel for removing pinstripes and adhesive off body panels to get more of it off. I got the majority of the old adhesive off the rim, how clean does it have to be?

I also took a latex “sander” eraser and removed all the dried sealant that was on the bead of the tire. The bead is looking really good now.

Sounds like you are still in the process of fixing it :slight_smile:

One thought is to consider what has changed since the flat: The sealant will have aged over time (but you’ve replaced it already). Perhaps the tape was disturbed in the process (but you’re redoing that). And the tire is punctured.

I’ve heard that some previously tubeless riders are now enjoying the new TPU tubes.

Have you replaced the valve or maybe just the valve core?

Have you put inflated tire in water to see if bubbling somewhere to ID leak spot?

Just brainstorming some troubleshooting ideas I’ve seen others try.

The rim doesn’t have to be super clean. The sealant will help seal small leaks at the tape/rim interface. Just need to make sure the tape is centered on the rim and covering the spoke holes.
I’ve had more problems with the tubeless values then the tape. The rubber at the bottom of the valve doesn’t always seal properly. I’ve used a small amount of Goop around the valve to help prevent that.

But in general the best way to find the problem is to fill the tire to a reasonable amount (like 40+ PSI) and then spray the tire an rim with soapy water. I usually keep an old spray bottle on hand filled with water a bit of dish soap. Any leak is usually easy to find. If there are bubbles near the value then it is likely the valve seal. If there are bubbles coming from the spokes around the wheel then it is likely the rim tape. Otherwise it is likely a problem with the tire.

Thx for the tips.

I spent more time with the rim and went at it with goo gone again.

I think the trick is to have the googone sit for about 10 mins to give it time to attack the adhesive.

The rest is just elbow grease.

I went at it 4 more times with googone and its now almost surgically clean.

I washed the goo gone off with soap and water.

Now, waiting on the rim tape. I’ll IPA the rim before applying the tape.

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Wow, that’s a clean rim!
Also, that latex “sander” block seems to really do the trick on the tire getting rid of the old dried sealant buildup.

I’d check the valve core to make sure it hasn’t come loose.

Otherwise I’d double layer the tape and at that point it is probably a tire issue.

If it doesn’t seat in 30 seconds then something is off. Sometimes that is just gummed up valve. I tend not to clean rims to much but if switching brands of tape that can be a problem. I had one wheel that took 3 attempts this year after rushing and switching from gorilla tape to stans.

On that, yes gorilla tape works really well, but I’m done with its residue.

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When I have run into pressure issues it has more often been a valve issue than a tire or tape issue. If the valve is too loose it will lose pressure but also if it is too tight. just hand tighten without extra force.
Make sure as others have said to use soapy water to check for leaks

The only sure fire way to fix tubeless setups: put a tube in :sweat_smile:


Tire reinstalled. Testing for leaks.

(it went from 60psi down to about 20psi the 1st time I pumped it up with sealant in it)

Now that I threatened to switch to my Goodyear connector tires, it’s decided, that it might hold air.

Laundry sink half full of water.

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Yeah, I find sometimes the initial install with fresh sealant can be slow to seal up.

FWIW, I just put on a set of goodyear connectors this spring and have been very happy with them. Setup was easy, bead snapped into place first try front and rear.

(I’ve sworn off any Panaracers after having many flats of my own and witnessing many others.)

yeah, the panaracers GK slicks could be on their way to the bin. Rode 50 minutes today and the tire seemed ok… Did the thumb check when I pulled back into the driveway and they were still firm.

Couple hours later, did the thumb check and they were soft again. Pumped them back up and put them in the laundry sink which I hadnt drained yet, and no bubbles. I pumped them up to about 40psi according to my Cdn Tire pump.

They were nice and smooth since I got them last fall. Front tire hasnt been an issue, they were relatively fast for my measly NP of 160-170 and 90kg.

So just a word of advice, be careful riding with tubeless especially if you’re having any sort of issues.

I had my front tire randomly “burp” after the bridge on Three bridges and it went from 40psi to ~5psi nearly instantly. Almost saved it but went down pretty hard around 30kmh and have lots of road rash and 3 broken ribs to deal with.

Never had any issues with the tire before and didn’t have a puncture. Mike at McPhails thinks the tire was likely faulty.

I’m going back to tubes.