This is the system used by California State Parks for their State Vehicle Recreation Areas (SVRAs).
Easiest | 1-3 | Relatively flat, these trails or fire roads provide a good starting point for beginners. |
More Difficult | 4-7 | Steeper and narrower, these trails usually have plenty of room to turn around at the top or bottom or have an outlet so that riders can avoid returning on the same route. |
Most Difficult | 8-10 | Steep and narrow, these trails often do not have an outlet; therefore, riders must be able to negotiate the trail in both directions. Only the most experienced riders should travel these routes. |
Note: Trail ratings are highly subjective. A trail that is easy for an experienced driver with a highly modified vehicle may be impassable for a novice driver in a stock vehicle. Weather conditions may also significantly affect the difficulty of a trail. Also, the difficulty of a trail may change over time, as trail use, weather, and maintenance modify the trail. Always check with the managing organization and/or recent users before planning a trip on a trail and scout ahead on foot if you are not sure of current conditions.