Motorized and mechanized travel on BLM ground is restricted to existing, mapped and signed routes. The BLM Murphy Travel Map should be consulted for legal motorized access by vehicle type for this area. Some trails are misrepresented as to access type in popular map apps and BLM's own online Recreation Access map due to width/vehicle-class errors in BLM's GTLF GIS data tags.   
BLM GeoPDF Maps: https://www.blm.gov/maps/georeferenced-PDFs/idaho and scroll to Owyhee Field Office listings. 
See IDPR's Idaho Trails web mapping app at https://arcg.is/C1SHr2 for a corrected representation of motorized routes and trails authorized under the BLM Murphy Travel Management Plan at the Hemingway Butte Trailhead.