Abstract: The invention describes both a method for bonding at least two elastomeric substrates together, wherein one of the substrates is a tire casing and another substrate is a tire tread, and an aqueous color changeable adhesive for effecting the bonding. The method includes the steps of buffing at least one surface of at least one of the substrates to an RMA 2 or RMA 3, applying the color changeable aqueous adhesive to the at least one surface, drying the adhesive for at least a period of time to permit an initial light grey color of the adhesive as applied to change to a flat black, and contacting the substrates under pressure to bond the substrates together. The color changeable aqueous adhesive includes at least a rubber latex emulsion, a tackifier, a pH adjustment agent, and a carbon black emulsion, wherein the carbon black functions both as a reinforcing agent and a visible color indicia means for evaluating the degree of dryness of the adhesive, which correlates to the degree of tack of the adhesive.