Your best bet is the get the TOPO US 24K, $100, from Garmin, you can then access/view it in MapSource. In MapSource you can also choose which areas you want to send to your Garmin, that way you dont have to load the entire US onto your unit and fill the memory..unless you have a big SD card and then you dont need to worry about it.
TOPO US shows all the Forest Service roads and has the contour lines you are asking about. If you want TOPO maps specific to snowmobile trails you need to get those from a local club that had them made for the area or search the web for a company who has made them for it.
I tried to do a custom map and overlay my sled trails onto a TOPO Map, but the Rino's wont recognize them...only the Oregon's and Colorado's.
Here's a good aftermarket TOPO for Minnesota.
http://www.gpsfiledepot.com/maps/view/153/
I have the one for Washington and its way more detailed than Garmin's, if you want to get that fine of detail.
Here is one that is snowmobile trails specific for Minnesota:
http://www.redpinemapping.com/minne...3.html?zenid=b6a7a1c09a2a86412a0f9ccf8535b7c9
Once you get it dialed in, it's awesome. Get used to using MapSource & BaseCamp, both avail for free from Garmin's site. BaseCamp is very cool to export your ride from your unit to. It can display your trip in 3D contour maps. Both MS & BC both have their strengths and weaknesses, once you learn what they can and can't fo and how to use them to their fullest, you'll be stoked.
Hope that helps