Many trustworthy sites across the web allow you to download free GPX files that can be uploaded/import to TRX Trailhead site or TRX device so that you can ride these trails.
Some good sites for downloading GPX files include:
- https://www.trailsoffroad.com ("...guides for over 2,000 trails in the United States, reporting on the conditions of those trails, and updating them four times per year...")
- http://www.jeeptheusa.com (Arizona, Colorado, New Mexico, South Dakota, Utah and Wyoming)
- http://www.traildamage.com (Colorado, Utah, California, Arizona, Texas, and Wyoming)