The ornamental design for tractor, as shown and described.
The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
1. Tractor
1.1 : Right side view
1.2 : Left side view
1.3 : Rear view
1.4 : Front view
1.5 : Top view
1.6 : Perspective view
1.7 : Partial enlarged front view
1.8 : Partial enlarged left view
1.9 : Partial enlarged top view
1.10 : Partial enlarged perspective view
The portion colored with gold (yellow and orange) forms no part of the claimed design; a bottom view is omitted because it is plain and unornamental and forms no part of the subject matter of the claimed design.