In most cases the bad bead sealing between the tyre and rim can cause lose the pressure. When your tyre can lose the pressure slowly and we can’t find any puncture we check the edge of the rim.
The simple water isn’t enough for the detection. We need to use a kind of liquid that can make bubbles. The bubbles on the edge of the rim show us the proper place of bad bead sealing.
We take off the tyre, clean the edges (both the tyre and rim) and (before we fit the tyre) use the special bead sealer (like ‘liquid rubber’) for repair it. After this we need to balancing the wheel because the tyre and rim can rotate relative to each other.
Typically, oxidation of the rim material or rim paint causes a change through which air escapes. Because this lesion is not visible, the error cannot really be noticed. After cleaning the surface, apply a special airtight material (called liquid rubber) to the rim of the rim before refitting the rubber. A similar phenomenon can occur where the rubber valve and the rim meet.
Unfortunately, the repair requires the tire to be removed from the rim in both cases.