The ornamental design for a tiltarmassembly, as shown and described.
FIG. 1 is an isometric view of a tilt arm assembly;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a left side elevation view thereof;
FIG. 5 is a right side elevation view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken line showing of the tilt arm assembly is for the purpose of illustrating portions of the tilt arm assembly and forms no part of the claimed design.