I claim the ornamental design for a tub for washing machine, as shown and described.
FIG. 1 is a front/right-side/top perspective view of a tub for washing machine showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left-side elevational view thereof;
FIG. 5 is a right-side elevational view thereof;
FIG. 6 is a top elevational view thereof;
FIG. 7 is a bottom elevational view thereof; and,
FIG. 8 is a front/right-side/bottom perspective view of the tub for washing machine.
The broken line showing of details in FIGS. 1-8 is included for the purpose of illustrating environmental portions of the tub for washing machine and forms no part of the claimed design.