The invention relates to an inner gum for a tyre, that has a rubber composition containing at least one butyl rubber, a reinforcement filler and a plasticising system, characterised in that the composition further includes graphite and in that the plasticising system includes a hydrocarbon plasticising resin having a glass transition temperature Tg higher than 20 DEG C and a softening temperaturelower than 170 DEG C. The invention also relates to a method for preparing a composition for a tyre inner gum, containing at least one butyl rubber, a reinforcement filler and a plasticising system, characterised in that the composition further includes graphite and in that the plasticising system includes a hydrocarbon plasticising resin having a glass transition temperature Tg higher than 20 DEG C, said method comprising the following steps: incorporating to a diene elastomer in a blender, a reinforcement filler, graphite, a plasticising system while thermo-mechanically kneading the mixturein one or more phases in order to reach a maximum temperature of between 110 DEG C and 190 DEG C, cooling the mixture to a temperature lower than 100 DEG C; further incorporating a cross-linking system; and kneading the mixture up to a maximum temperature lower than 110 DEG C.