The ornamental design for a tirevalvecap, as shown and described.
FIG. 1 is a top perspective view of a tire valve cap showing our new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a side elevational view thereof, all other side views being the same thereof;
FIG. 4 is a bottom plan view thereof; and,
FIG. 5 is a bottom perspective view thereof.
The broken lines showing structural features are included for the purpose of illustrating non-claimed subject matter and form no part of the claimed design.