Tethys Tethys from Grant Mason Tethys Tethys is a simple suburban/city vehicle. The exposed frame and compact 3-wheel architecture are a fun combination of commuter car and motorcycle. gLike Tethys Tethys is a simple suburban/city vehicle. The exposed frame and compact 3-wheel architecture are a fun combination of commuter car and motorcycle. Industrial Design Engineering Share R 7 n Available Grant Mason Design and Engineering Leader Foxborough, MA Follow Contact