A method to produce a compound for a tyre sealant layer, comprising a swelling step, during which a crumb rubber is immersed in a process oil chosen among the ones belonging to the families of paraffin process oils, naphthene process oils or natural process oils, so as to obtain a crumb rubber that swells due to the absorption of the process oil; and a following mixing step, during which said swollen crumb rubber is mixed with at least one polymer base consisting of an essentially saturated polymer.