The section of Angeles Crest Highway between Islip Saddle and Vincent Gap is normally closed to car traffic in the Winter, and left unplowed. In this condition, it's usually possible to park at either end, and ski ~10 miles to the other end. The road rises monotonically from each end to the midpoint at Dawson Saddle. The gain is slightly less from Islip Saddle, which is a bit high in elevation than Vincent Gap. But either way, it's all downhill on the return trip.