A set of tiles adapted to cover a surface perpendicular to a thickness direction of the tiles, each of the tiles comprising at least one upper layer, and an underlying rigid core layer, the core layer and the upper layer being superimposed in the thickness direction, and the core layer defining a lower surface opposite the upper layer, wherein: - the tiles comprise at least one first tile having a first edge extending in a longitudinal direction, the core layer of the first tile defining a connecting groove in the first edge, - the tiles comprise at least one second tile having a second edge extending in the longitudinal direction, the core layer of the second tile defining a connecting tongue protruding from the second edge, the connecting tongue being adapted to be snap-fit into the connecting groove in a connecting direction perpendicular to the longitudinal direction and to the thickness direction in a locked configuration of the first tile and the second tile, - the lower surface defines an additional groove parallel to the first edge, - the connecting groove defines a lower contact surface adapted to be at least partly in contact with the connecting tongue in the locked configuration, - said lower contact surface has a locking part adapted to abut against a matching surface of the connecting tongue when the second tile is moved away from the first tile in the connecting direction starting from the locked configuration, and has a blocking part adapted to abut against a matching surface of the connecting tongue when the second tile is moved toward the first tile in the connecting direction starting from the locked configuration, and - the locking part and the blocking part are in contact respectively with said matching surfaces (64, 68) in the locked configuration, and - are inclined with respect to the thickness direction so as to block the connecting tongue with respect to the connecting groove in the locked configuration when a pressure is applied on the upper layer of the first tile in the thickness direction toward the connecting groove, characterised in that - the lower contact surface has a lowermost point in the thickness direction, and - the locking part and the blocking part are separated by the lowermost point. - the tiles comprise at least one first tile having a first edge extending in a longitudinal direction, the core layer of the first tile defining a connecting groove in the first edge, - the tiles comprise at least one second tile having a second edge extending in the longitudinal direction, the core layer of the second tile defining a connecting tongue protruding from the second edge, the connecting tongue being adapted to be snap-fit into the connecting groove in a connecting direction perpendicular to the longitudinal direction and to the thickness direction in a locked configuration of the first tile and the second tile, - the lower surface defines an additional groove parallel to the first edge, - the connecting groove defines a lower contact surface adapted to be at least partly in contact with the connecting tongue in the locked configuration, - said lower contact surface has a locking part adapted to abut against a matching surface of the connecting tongue when the second tile is moved away from the first tile in the connecting direction starting from the locked configuration, and has a blocking part adapted to abut against a matching surface of the connecting tongue when the second tile is moved toward the first tile in the connecting direction starting from the locked configuration, and - the locking part and the blocking part are in contact respectively with said matching surfaces (64, 68) in the locked configuration, and - are inclined with respect to the thickness direction so as to block the connecting tongue with respect to the connecting groove in the locked configuration when a pressure is applied on the upper layer of the first tile in the thickness direction toward the connecting groove, characterised in that - the lower contact surface has a lowermost point in the thickness direction, and - the locking part and the blocking part are separated by the lowermost point.