For the Spring Mountains National Recreation Area, the US Forest Service has their official MVUM (motor vehicle use map) available online here...
MVUM - Spring Mountians.
It is the official map that USFS uses to manage/enforce motorized vehicle use.
You can pick up a free paper copy at the BLM/USFS office at,,,
4701 N Torrey Pines Dr
Las Vegas, NV 89130
Phone (702) 515-5400
BTW - USFS has developed, or is in the process of developing these maps for all National Forests. Here is a link to the master list of MVUMs... US Forest Service MVUM by State and Forest
What trail systems are you specifically referring to?Where can I find a map of all the listed trail systems I see when I'm out?