From I-70 at Copper Mountain, take State Highway 91 across Fremont Pass to Leadville. In Leadville, turn east onto East 7th Street from the "downtown" area which will become CR3 and drive to the vicinity of Diamond and Mountain Lakes. The road is well-maintained and easily passable for passenger cars up to about 11,200' near some old mines, after this point, it quickly becomes rough & rocky. Vehicles with higher clearance may be able to proceed further, depending on the driver's disposition. We suggest parking out of the way by driving on a spur road toward the Conley Lakes. See TH coordinates, or park where convenient or where the road begins to become even rougher before it begins its climb to the pass (approx. 12,000').
If attempting to 4-wheel all the way up the pass, the road is decently passable (although relentlessly rocky) in stock high-clearance 4x4s up to a switchback at 12,440'. The section of road between the two switchbacks located at 12,440' & 12,600' is the roughest section on this side of the pass. The switchback at 12,600' has deteriorated in recent years and, depending on current conditions, stock SUVs may scrape bottom a bit going over a few rocks here. We hiked this road in 2015 and saw a Ford F-150, Nissan XTerra, and stock Jeep Wrangler all navigate this section, but none did so without contacting rock on the undercarriage at some point. Past this point the road remains quite narrow with very few pull-offs, but the degree of difficulty relents a bit as it approaches the summit.
Also, after the last switchback, there is a spur road that heads off to the right and in a SSE direction to access some radio tower facilities. In 1989, it was possible to drive this road all the way to the central ridge and begin hiking from there. Current condition of that road is unknown.
Along CR 3, you may be able to find a place to park overnight, but be careful about Private Property all through this area.