A pneumatic tire whose inner wall is provided beneath the crown with a lining which extends at least from one shoulder to the other of the tread and comprises a layer of a sealing mixture capable of flowing into a puncture hole, the layer being covered radially inward by a vulcanized elastomeric partition, is improved due to the fact that the layer of sealing mixture has a base of at least one elastomer of low molecular weight, preferably less than 30,000, mixed with at least one thermosetting resin, and due to the fact that at least one cross-linking agent or hardener for the thermosetting resin is isolated from the layer of sealing mixture by means of a vulcanized elastomeric partition arraged radially inward of the layer of sealing mixture.