The ornamental design for a tiering, as shown and described.
FIG. 1 is a perspective view of a tie ring showing my new design;
FIG. 2 is a rear elevation view of the design of FIG. 1;
FIG. 3 is a top plan view of the design of FIG. 1;
FIG. 4 is a front elevation view of the design of FIG. 1; and,
FIG. 5 is a right side elevation view of the design of FIG. 1.
The design consists of the features of shape and configuration of the entirety of the tie ring as shown in solid lines in the drawings. The portions shown in stippled lines do not form part of the design.