I have a Garmin and I use the text files from this site. They can be converted to be used in a Garmin device.
http://www.discoveryowners.com/cginfo.htm
Use this site to convert. I have not used this program but the support at Garmin gave me the site location.
http://www.gpsvisualizer.com/convert_input
or use the POI loader from Garmin. This is how I loaded the low clearance.
https://support.garmin.com/support/s...00000000000%7D