The Clear Creek Management Area (CCMA) is a network of OHV roads and trails. A TOPO! version of their network is attached to this page, but you can also refer to the map on CCMA's web site
For those most part, just find a place along the road where your vehicle is not obstructing the road. Keep in mind that rather large trucks with rather large trailers travel these roads and need a wide berth.
If you're parking near Idria, be especially mindful of the private property issues. Of course, the road is public, but the local(s) take their property seriously.
Four Wheelin' or Hikin'
From the town of New Idria, the round trip mileage is approximately 15 to 16 miles, depending on your exact route. The further you drive your car, the less mileage you’ll have to hike. Roads and trails are marked by brown plastic signs. The easiest route to the top from New Idria is the main road (R011) to the CCMA sign approximately 3.5 miles from town, and then continue on Road R011, which goes up the San Carlos Creek valley. At the head of the valley, turn right onto Road R013 and right again onto a road (R012) marked “trail.” That takes you right to the very peak, no hiking necessary with a 4WD. If you’re hiking along this road, expect encounters with OHVs. Luckily, you can hear them coming.
Recommended Hiking Route
I recommend hiking R011 just beyond the CCMA sign and taking Road R014 out of Aurora Mine and up to the ridge that is south of San Carlos Creek. From here, you can follow R010 along the ridge to the summit. As of 25 February 2006, R010 was closed to motorized traffic, making it significantly quieter than other approaches.
To make a loop that avoids most of the OHVs, try descending via T156, which follows the ridge to the north of San Carlos Creek. You can make a side trip up San Carlos Peak, but there isn’t much extra to see from up there and it requires a short bushwhack. There is a very cool, uncovered mine shaft near the top of San Carlos. Watch your kids and pets: we dropped a rock in it and didn’t even hear it hit the side until after 8 seconds! T156 transitions to T154 and T153 near the man-made lake, but just keep heading down and you’ll end up where you want to be.
Sturdy footwear, water, map, and your typical Ten Essentials. Check conditions before your trip for potential rain closures, asbestos warnings, and OHV races.