Are you looking for a route from SD to Yosemite that is all dirt? I don't know of any that connects the two thats entirely dirt but you can probably map one out that is close enough. Yosemite itself and surrounding mountains don't have much to any truck trails, mainly just single track, but just outside there's plenty. Take a trip up the 395 and you'll cruise through so much. Outside of SD you have a few simple trails and Anza has plenty of trails to drive around. Between SD and Yosemite there are too many to list but the popular ones are Mojave, Cleghorn, everything in Bear, Salton Sea area, Indio...the list goes on.