I did twice Black Mountain Trail/Forest 4S01 from 243, all the way to Pacific crest trailhead. During summer time it was very easy - any high clearance SUV can do, I did it on my 4R stock. Last year in March I believe, it was also pretty easy with some snow on the top, but once I hit northern part of the mountains I stuck there on my bold tires, with my friend driving Lexus, and another guy on brand new Range Rover. Three 4X4 cars in deep wet snow going uphills. Spent there about 3-4 hours trying to get out, then we were fortunate a guy came there on Rubicon with 35" tires and winch. After about an hour and a half of winching we all get back on top and on trail. So, be careful once you see downhill road covered with snow, it most likely deep and it will be really hard to get back.