The ornamental design for a wall-mountable towel bar, as shown and described.
FIG. 1 is a right front perspective view of a wall-mountable towel bar in accordance with my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a top plan view thereof, the bottom plan view being identical;
FIG. 4 is a right side elevational view thereof, a left side elevational view being a mirror image thereof;
FIG. 5 is enlarged fragmentary view of a portion of the design shown in 1, with the remaining portions omitted from the disclosure merely for clarity of illustration;
FIG. 6 is enlarged fragmentary view of a portion of the design shown in 2;
FIG. 7 is enlarged fragmentary view of a portion of the design shown in 3; and,
FIG. 8 is enlarged fragmentary view of a portion of the design shown in 4.
The rear elevation view of the wall-mountable towel bar is not shown in the drawings or described in the specification and, therefore, forms no part of the claimed design.