If a replacement tube soon goes flat, locate the damage first. A small single hole often points to a sharp object in the tyre; two adjacent cuts suggest an impact pinch. Damage on the inner circumference calls for a rim inspection. Check both tread and tyre interior: glass or a thorn may still be embedded.
Rim tape shields the tube from spoke holes and metal edges. It must suit the rim and fully cover the holes; tape that is too narrow can shift. Hollow-section rims need appropriate high-pressure tape, since ordinary rubber strips can be forced into the holes. Correct damaged or displaced tape before fitting a fresh tube.
A small hole in a conventional butyl tube may be repaired with a suitable patch. Lightly prepare the surrounding area, clean it and let it dry fully. With vulcanising patches, allow the adhesive to dry as directed before applying the patch. A tube patch cannot repair a torn tyre casing: an internal tyre boot is temporary, and the damaged tyre needs replacement.