a thermosetting adhesive comprising a bismaleimide compound and an isocyanate - terminated rubber polymer adapted to coreact upon heating is applied to substrate surfaces of a cured polyurethane and an uncured rubber compound . upon heating , the adhesive crosslinks and the uncured rubber compound is preferably cured simultaneously . the adhesive is particularly useful in the fabrication of compositions by the bonding of cured polyurethane to an uncured rubber compound which becomes cured during the bonding process , such as in the construction of tires containing cured polyurethane reinforcements within uncured rubber carcasses , the retreading of tires containing polyurethane repairs , etc .