First, I recommend you read our article with the basic steps to make tubeless/taping a MTB wheel.
THE TUBELESS LEAKS AIR AND IS DEFLATED AFTER A FEW DAYS: WHY?
There is almost certainly a lack of liquid (sealant/latex) inside the tire and micro leaks have been created which cause the tire not to hold the pressure. I remember that, every 2-3 months, the latex must be checked and, if necessary, topped up (in the warmer months it can evaporate more quickly).
If even after topping up the latex the wheel continues to "spray" from the hole, it means that the hole is too large and can only be resolved with vermicelli (or by returning to the inner tube setup).
HOW TO RESOLVE A TUBELESS PUNCTURE
Another reason for air leaks in a Tubeless can be a shot at the rim which has created a dent (draft) and therefore air escapes from that point. How to solve? Trying to straighten the rim with a special tool but be careful: if the dent is serious, you may not be able to solve the problem and will have to solve it by returning to the inner tube configuration.
WHAT ARE THE MAIN REASONS FOR AIR LEAKAGE FROM THE VALVE?
The sealing tape, which makes the wheel "watertight", has become ruined and therefore the air tends to escape from the valve, the wheel's only vent point. How could this have happened? It is often the fault of the use of tire levers when inserting/removing the tyre, which can damage the tape inside.
Solution? Remove the tire and remove the tape, leaving the rim to dry well. Once dry, replace the sealing tape and reassemble the tire with its liquid.
HOW TO LATETICize A TUBELESS MTB TIRE

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