Tubeless leaking - should I be worried?

Hi everyone,
two months ago I entered the tubeless world with my new Gravel bike.
Mounting the tires (700x38C) and filling in the sealant (Finish Line) went better than expected. Also the first few rides were above reproach.
But then it started: After one ride I noticed a few blue splatters on the frame and my back. Seemingly the sealant did what it should do - clogging a whole in the tire - with some “collateral damage”. During the ride I noticed nothing.
A few rides later the same thing happened again, this time with more splatters. The tire still holds the pressure (3 bar, 43psi) well.
Since then, I find these splatters after each ride. Even if only ride on “clean” roads, where I can assume not to have hit anything that punctures the tire.

Is this behavior normal? Should I change the sealant?

Have you inspected the tire(s) to see where they are leaking?

In some case, you may have a large puncture that is popping, leaking, and resealing. If so, you should look into tire plugs (many options to consider) to more “permanently” seal the hole and not rely entirely on the sealant.

Depending on the amount you have lost over time, you may also want to refill the sealant.


Thanks for sharing your experience.
With a quick optical inspection of the outside I wasn’t able to find anything that still sticks in the tire or any damages - only some areas clotted with tire sealant between the knobs (Ihave also done this after the previous rides).
I guess I have to clean the tire thoroughly and then repeat the inspection to find the punctures before trying tire plugs.
Anything special to watch for when buying tire plugs?

Ive had good success with finish line. But you have to use 1-2oz more per tire than recommended. Inspect where it is leaking from. If it’s small, then it may take a few rided before it totally seals and stops liquid slowly seaping out. And im talking droplets of leakage, not spraying. Once some fibers get in the puncture, it should totally seal as long as its not huge. If you feel you have lost a lot of sealant, you could put more in.

If it still holds pressure throughout the ride, I don’t think it needs a plug yet.

We have a lengthy thread on the topic with great info to review:

Thanks for the link.
I guess I will first study this (and also some other resources) before taking other action.

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I’m not sure if it “sprayed” as I didn’t notice anything during the ride.
I just found ~20 small (1…5mm diameter) dried drops on the frame. For sure there also were others that didn’t hit the frame.

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What kind of tires? Some tires seep sealant. I’m having that issue right now with a continental cross king on my MTB.

Wouldn’t worry about it just yet.

Next time check your tire pressure before and after the ride and note the psi drop.

BTW, if/when it comes time to repair the tire, only plug it if you’re on the road. If you’re home, patch the tire from the inside, using a standard cheap tube patch.

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Schwalbe G-One Allround.
I don’t think the tires are the problem because a) it is only on the rear tire and b) there are only some spots on the rear tire’s surface that show stains of dried sealant.

I’ve inflated the tires to 3bar (43.5psi) on Tuesday, rode Tuesday and Thursday for about an hour.
Now (Friday) the front tire (showing no sealant stains) has 2.75bar (39.9psi) and the read tire is down to 2.5bar (36.6psi), corresponding to a loss of 3.6psi (front) vs. 6.9psi (rear).
From what I’ve read elsewhere this is still within limits.

Using patches (instead of plugs) when at home makes sense.

Today I had another look at the tire: I still can’t see any punctures from the outside (contrary to my road bike tires with latex tubes where I easily can spot many).
At least one spot seems not to be fully sealed because the sealant stains are not completely dry, indicating that sealant continues to leak.