Granted it wasn't Yellowstone, but last year my brother-in-law and I rode at Cooke City last winter. Its basically just up the road from the Yellowstone park gate. Had a blast! Would highly recommend it. I rented from Cooke City Motorsports. They were very down to earth and fantastic to rent from. Their prices were reasonable as well. 
	
		
			
		
		
	

	
		
			
		
		
	
			
			
 
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