A method for making a compartmentalized sealant strip and barrier assembly 10 has the steps of co-extruding a barrier strip 9 of non-sealant elastomeric material with a plurality of projecting linear extending walls 9c and a sealant strip 11 wherein the sealant strip 11 is formed on one side of the barrier strip 9 filling the space between the plurality of projecting walls 9c to form a plurality of linearly extending rows of sealant 11 across the transverse width of the co-extrusion to form the compartmentalized sealant strip and barrier assembly 10. The step of co-extruding may further include the step of: forming the projecting walls 9c on an inclined angle relative to a plane perpendicular to the width of the assembly 10. The step of co-extruding further has the step of forming the barrier strip 9 with lateral edges 9a and 9c that extend beyond the lateral outermost sealant strips 11 on each side of the assembly 10, the lateral edges 9a, 9b being bonding surfaces to seal the sealant strip and barrier assembly 10 into an uncured rubber layer when assembled into an unvulcanized tire 2.