A slider window assembly for a vehicle includes at least one fixed window panel and a frame portion attached at the at least one fixed window panel. A movable window panel is movable along upper and lower rails of the frame portion and movable between a closed position and an opened position. At least one of the upper and lower rails includes a recess for receiving adhesive therein and a tapered end region at an end of the recess. The tapered end region includes at least one notch or groove through a wall that at least partially circumscribes the recess, with the notch or groove configured to allow excess adhesive to escape during the adhesive bonding of the at least one of the upper and lower rails to the at least one fixed window panel. The tapered end region has an outer tapered surface opposite the recess.